You have no items in your shopping cart.

You have no items to compare.

Oil FAQ

What motor oil is best for my Porsche or high performance engine?


by Charles Navarro
Last Updated 10/10/2023

What is the best oil for my Porsche?

Any information you may receive related to this commentary is provided merely as friendly suggestions, not as expert opinion, testimony or advice.


The purpose of proper lubrication is to provide a physical barrier (oil film) that separates moving parts reducing wear and friction. Against popular belief, metal to metal contact does occur and these surfaces are highly dependent on a strong and robust anti-wear film. Oil also supplies cooling to critical engine components, such as bearings.  The viscosity of the motor oil throughout the operating range of the engine is very important to the “hydro-dynamic bearing” layer of oil film that forms on and between moving engine parts. Where metal to metal contact occurs, boundary lubrication occurs when insufficient film to prevent surface contact and where the primary anti-wear additive ZDDP plays its role in protecting your engine.  Detergent oils contain dispersants, friction modifiers, anti-foam, anti-corrosion, and anti-wear additives, all of which can affect the strength and durability of anti-wear films. Not sure what you need to know about oil? You don't need to be a tribologist. Just remember the 4 R's when choosing the best oil for your engine: the right oil in the right place at the right time and in the right amount.

Not all motor oils are created equally when it comes to the levels of additives and detergents used. These detergents carry away contaminants such as wear particulates and neutralize acids that are formed by combustion byproducts and the natural breakdown of oil, but can also inhibit the formation of ZDDP anti-wear films on critical engine components. In an SAE whitepaper on the development of the API SL standard, Shell’s own lubrication engineers stated that ‘the introduction of ash-less and zinc free oils are on the horizon making choosing an oil that much more difficult for older engines.’ The focus of this study is on the levels of zinc and phosphorus found in motor oils, more exactly, the zinc (Zn) and phosphorus (P) that makes up the anti-wear additive ZDDP, zinc dialkyl dithiosphosphate. Oils for modern engines have different formulation constraints than those for older engines and just because oils are “modern” or synthetic does not mean they will provide adequate protection for your engine. Shopping for oil by brand, previous reputation, or by manufacturer approvals alone does not guarantee the best oil for your classic car or performance engine.

Even prior to the introduction of the SM, SN, and SP API standards, there was concern that the then current API SL standards from back in 2003 could inhibit the backwards compatibility of motor oils. This was specifically in reference to the limitation of ZDDP, which is considered "the most effective combined anti-wear and anti-oxidant additives currently available." SAE 2003-01-1957, Effect of Oil Drain Interval on Crankcase Lubricant Quality, Shell Global Solutions. The authors stated that these modern oils are required to provide longer protection in severe operation but that an oils performance is "limited by environmental considerations." Furthermore, they stated that it is hard to predict the effects of these reformulated oils in just a single oil change and may only be evident over an engine's lifetime. It is hard to know the full extent of the potential damage these new oils will have on our performance engines, so chose your lubricants carefully.

What general characteristics make motor oils specifically well suited to a particular engine? Aside from recommendations issued by the manufacturer, what makes for a good motor oil? These oils must be thermally stable, having a very high flashpoint, low noack volatility, and must “maintain proper lubrication and protect vital engine components under the extreme pressure and the high temperature conditions.”

For example, for aircooled Porsche engines, 15w40 viscosities are recommended below 80F ambient air temperatures and 20w50 should be used in hotter climates above 80F. Porsche recommends and uses Mobil 1 0w40 as a factory fill in new vehicles and Mobil 1 15w50 has been a popular choice used by many year-round in aircooled Porsche models, but most Porsche specialists agree there are better choices available. What was once considered a 'safe' oil is no longer, as many of these lubricants have been reformulated for many reasons. This includes for protection of emission control devices, increased fuel economy, and longer oil change intervals. As mentioned previously, shopping by brand alone or following manufacturer recommends no longer ensures satisfactory performance.

Using a factory approved or recommended oil also doesn’t necessarily guarantee the best results, however if your vehicle is under warranty, it is always advisable to use an oil carrying manufacturer approval to protect your warranty. Simply cutting the factory recommended interval in half both for time and mileage will provide significant improvement when using factory approved oils. Outside of warranty requirements, the available options for lubricants become much greater. According to Lake Speed Jr., a certified tribologist and one of the founders of Driven Racing Oils, when choosing a lubricant, you need to remember the 4 R’s: the right oil, in the right place, in the right quantity, and at the right time.

It is worth noting that Mobil offers its own line of racing oils for track use and Porsche even now offers its own line of classic oils for protecting older aircooled engines and even specialty oils for watercooled 986 and 996 models, so oil selection is more important now than ever. Understanding what changes have been made, and why, is important in selecting the right lubricant. Porsche’s recommendation in hand, our initial analysis from 2005 and 2006 and from virgin oil analyses going back to the 1990s, we found that then prior SH/SJ formulations of Mobil lubricants tested, including Mobil 1, have had higher Zn and P content than what is found in current API oils. Even those products intended for classic car and performance engines that have "re-introduced" have been reformulated and are not the same was what was previously available. Aside from reduced Zn and P levels, many products with adequate levels of Zn and P still use very high levels of detergents. It is well documented in various SAE publications that high levels of Calcium detergent cause more wear than Ca/Mg or Ca/Mg/Na detergent blends that were commonly used back when the API SH/SJ standard was current. However the companies who make the oil additives have discontinued these older additive packages, requiring reformulation with additive packages designed for modern engines. Along with changes to detergents and detergency, the industry wide trend of the reduction of ZDDP to 0.06-0.08% by weight, or even worse, the elimination of these additives, makes modern oils unsuitable for classic car and performance engines.

As already mentioned, oil companies have been cutting back on the use of Zn and P as anti-wear additive, which is detrimental to classic car and performance engines that rely on these additives to prevent wear.  Depending on how detergent an oil is and which detergents are used, optimal Zn and P levels can range from 1200 to 1500 ppm, lower detergency oils require less ZDDP to provide adequate protection. The reduction of phosphorus content coming from ZDDP is a mandate issued by API, American Petroleum Institute, who is in charge of developing standing standards for motor oils, to meet EPA and manufacturer requirements.  ZDDP has been found to be bad for catalytic converters as well as gasoline (GFP) and diesel particulate filters (DPF).  In 1996, API introduced the API SJ classification to reduce these levels to a maximum of 0.10% for viscosities of 10w30 and lighter. The 15w40 and 20w50 viscosities commonly used in aircooled Porsche and other classic car and performance engines did not have a maximum phosphorus limit. The API SL standard maintained this higher limit but with reduced limits for high temperature deposits.  With the API SM, phosphorus content less than 0.08% was mandated to reduce sulfur, carbon monoxide, and hydrocarbon emissions. The biggest difference between the API SM and SN standard is that with the subsequent SN standard mandated a max phosphorus content of 0.08% for all motor oil viscosities, not just the 10w30 and lighter oils the previous API standard limited, and limits for high temperature deposits are reduced, requiring added detergency for increased engine cleanliness allowing for longer drain intervals. Oils meeting the most current API SN+ and SP standards retain the same limits for phosphorus content while adding protection for low speed pre-ignition, reducing Ca detergency to less than 2000 ppm and eliminating of Na detergents. Oils meeting the current API ILSAC GF-6A and GF-6B standards in 0w16 and thinner viscosities have also become commonplace . For these reasons, most modern oils are not backwards compatible with older engines.

It is worth noting that prior to this movement to reduce Zn and P levels, the oils recommended for use in an aircooled Porsche engine back in the 1990s typically had 0.14% Zn and 0.14% P content with less detergency, than found in later API SL-SM street car formulations. In comparison, an API SE-rated virgin oil sample of Kendal GT-1 motor oil from the 70’s, pre-dating today’s limited Zn and P mandates, contained 0.14% Zn and 0.12% P, again with significantly reduced detergency. These oils were run with relatively short drain intervals compared to those now recommended by most automobile manufacturers. Oils with later API SH and SJ standards with no limit for phosphorus were developed, tested, and used in aircooled engines through the end of production of the Porsche 911 993 model with aircooled Mezger engine. With this knowledge, it can be concluded that any given motor oil should have a minimum of 0.14% zinc and 0.12% phosphorus for aircooled engines, given an average 0.25% total detergent levels (which is the average detergency for API SJ rated oils). The lower the detergency, the less ZDDP is needed. Remember, it is all about additive balance!

Oil companies have been cutting back on the use of Zn and P as anti-wear additives and switching to alternative zinc-free (ZF) additives and ash-less dispersants in their new low SAPS oils since Zn, P, and sulfated ash can reduce the life expectancy or performance of emissions control devices. To offset the reduction of zinc and phosphorus levels required by the EPA and manufacturers, boron as well as molybdenum disulfide, among other friction modifiers, has been added to modern oils, since they do not foul the catalysts in the particulate emissions filters or catalytic converters. It is worth noting that most Porsches have lived the majority of their lives with high Zn and P oils as found in API SG-SJ oils, as late as 2004, and these vehicles never have suffer damage to the catalytic converters caused by high levels of ZDDP. The addition of boron, when in the presence of ZDDP, does boost the anti-wear properties. Although considered a friction modifier, moly does have benefits beyond increasing fuel economy to meet CAFE (Corporate Average Fuel Economy) fuel requirements enacted by Congress in 1975. Moly is an antioxidant and provides additional LSPI protection for modern gasoline direct injected engines. The inclusion of moly and boron alone do not completely address wear issues of classic car and performance engines that require higher levels of Zn and P. Cutting edge research being conducted at ORNL and by other researchers in the area of ionic liquids may possibly bridge the gap between fuel economy and wear requirements and provide true backwards compatibility for engine oils.

In addition to protecting emissions controls, there are many other design considerations in formulating engine lubricants, which include improving fuel economy and longer drain intervals. Many believe that the EPA has banned zinc and phosphorus in motor oils. This is not true. In response to modern engine design and longer emission control warranties which are required by the EPA, manufacturers have turned to reformulation of oils to do this, as well as to improve fuel economy by reducing fiction. High friction can result in areas with boundary lubrication or where high viscous friction forces and drag may occur with hydrodynamic lubrication in bearings. The use of friction modifiers, such as moly (there are many different species of Mo-based friction modifiers, help to reduce friction in metal-to-metal contact with the formation of tribofilms characterized with their glassy, slippery surfaces. Lower viscosity motor oils are key to increasing fuel economy by their reduction in drag where high viscous friction occurs in hydrodynamic lubrication. While lower viscosities improve fuel economy greatly, they also reduce the hydrodynamic film strength and high temperature high shear viscosity of the motor oil, factors both of which are key to protecting high performance engines, especially aircooled ones. It is worth mentioning that bearing clearances in modern engines may require thinner oils, making the formulation and levels of anti-wear and friction modifier additives that more important to reduce engine wear.

It is worth noting that these new API guidelines do not need apply to “racing,” “severe duty,” or any motor oils that do not carry an API “starburst” seal  or clearly state for off-road-use only.  Motor oils meeting “Energy” or “Resource Conserving” standards, that provide emission system protection, or extended drain intervals should be avoided as well as those with an API SM / ILSAC GF-4 or later (newer) classifications. Most 10w40, 5w50, and 10w60 viscosity grades, because of their lack of shear-stability and relatively high amount of viscosity improvers, should also be avoided, or at the very least, be run with significantly shorter oil change intervals than what is recommended by the manufacturer.

The European ACEA A3/B4 "mid-SAPS and full-SAPS" classifications, which place a cap on P levels at 0.10-0.12% but allow for higher Zn levels, to be better in taking into consideration wear and engine longevity, setting much lower wear limits, while still limiting emissions and protecting emissions control devices. A good example of this is a Porsche A40 approved lubricant for newer watecooled models - although it may carry an API SM or SN rating, it will by rule require 0.10-0.12% Zn to meet the ACEA requirements. The current ACEA A3/B4 classifications require higher high-temperature high-shear (HTHS) viscosities, stay in grade sheer stability, and tighter limits on evaporative loss (noack volatility), high temperature oxidation, and piston varnish. This makes oils meeting these ACEA standards that much better for your modern watercooled Porsche, especially since wear limits are much more stringent for valve train wear, 1/6th to 1/4th the wear allowed in the sequences for API's SM or CJ-4 standards. Likewise, where a choice between a 0w40 and a 5w40 is provided, as long as extreme cold start protection is not needed, the 5w40 with it’s narrower viscosity spread will retain its viscosity better and typically provide better protection, albeit at slightly lower fuel economy. Newer Porsche engines with direct injection and forced induction require oils formulated to protect against LSPI. The Porsche C20, C30, and C40 specifications have reduced levels of calcium detergents but also have reduced levels of ZDDP compared to an A40 oil. That said, if you don't need to use a factory approved oil for your Porsche, there are many choices that provide superior protection when not constrained by the requirements to gain Porsche approval. Specifically, modern Porsche engines with Lokasil or Alusil engine blocks can benefit from an oil with significantly higher levels of moly than what is allowed in a Porsche approved oil which provides increased protection against cylinder bore scoring.

Compared to conventional oils, synthetics have superior shear stability leading to improved resistance to thinning and evaporation at high temperatures. Synthetics also have superior cold flow characteristics, reducing start-up wear significantly. Although most modern synthetics incorporate seal swelling agents, for those concerned with formation of new leaks or worsening of existing leaks, an acceptable compromise is the use of conventional (group I or II), semi-synthetic, or group III synthetic oils formulated from very highly refined “hydro-cracked” petroleum base oil stock. Group IV PAO and group V ester base stocks are often blended with group III oils and marketed as full synthetic. Regardless of your choice to use conventional, partial, or full synthetic lubricants, the additive chemistry is just as important as what group base stock is used.

Failure to use the right oil, use proper filtration, or observe proper changing intervals can affect the performance of even the best motor oil. It is also worth noting that some manufacturers have gone to shorter intervals and requiring fully synthetic oils due to litigation surrounding sludge formation and failed engines as a result of factory recommended long drain intervals, so drain interval recommendations are often in a state of flux. At one point, European manufacturers were recommending very long oil change intervals, some in excess of 30,000 mi, not because that was best for the engine, but rather to reduce the total cost of ownership which is considered a part of a vehicle manufacturer's overall ratings. Fewer oil changes also on paper reduces the amount of waste oil and filters and perceived impact on the environment, however these benefits come at the expense of shorter product life. Most users have found it best to reduce those intervals by half or even a quarter in severe conditions. For example, Porsche over the last decade has stated oil change service intervals ranging from 12,000 to 24,000 miles and up to two (2) years, but has in recent years reduced this to one (1) year or 10,000 miles. Based on used oil analysis results shared with us by our customers, most Porsche owners should consider following a manufacturer's severe service recommendations, reducing oil change intervals to no more than six (6) months or 5,000 mi.

Vehicles that are driven spiritedly, used for autocross, or tracked are subjected to increased stresses that consume the oil anti-wear additives in the engine oil. It is also common for oils to shear out of grade as the viscosity modifiers breakdown. This viscosity loss can have a negative effect on engine wear. As a result, vehicles that are driven hard should have their engine oil changed more frequently. Cars that are taken to the track or raced should have their engine oil changed after every event. Likewise, vehicles subjected to very short drives or sustained operation in heavy traffic should indeed be serviced more often. Another factor to consider is fuel dilution, common to carbureted and direct fuel injected engines. Fuel is not a lubricant, so high levels of fuel in your oil will require more frequent oil changes. Lastly, vehicles that are not regularly driven should be stored with clean engine oil and have a fuel stabilizer added to the gas tank.

Coupled with reduced oil viscosities, modern engine oils are designed to maximize fuel economy, extend catalytic converter life, and reduce tailpipe emissions. It is more important now than ever to select the right engine oil for your classic car or performance engine. Regular used oil analysis is the best way to determine ideal drain intervals for your driving habits and ensure the oil you are using is the best for your engine. With this knowledge in hand, using a quality motor oil formulated for your application with proper filtration and reduced drain intervals, is the best thing to do to protect your engine.


Frequently Asked Questions

When in doubt, always refer to the manufacturer specifications and recommendations for lubricants and viscosities to be used.
 

Should I use a non-detergent oil to break in a new or rebuilt engine?

Just because non-detergent oil is cheap, it doesn't mean you should use a cheap non-detergent oil to break-in your new or rebuilt engine. In years past a non-detergent oil was recommended for engine break in as lack of detergents would allow the ZDDP to work better. We now have better oils for engine break in than non-detergent oils. Always use a proper break-in oil in a new engine. Under no circumstances should a partial or full synthetic oil or any oil that has friction modifiers (moly) be used for break-in of a new or rebuilt engine.
 

How should I break in my new or rebuilt engine?

If you have questions on how you should break in an engine and proper break in procedure, we recommend reading the following articles about the subject:

http://www.mototuneusa.com/break_in_secrets.htm

http://www.aircooled.net/vw-engine-break-in-procedure/
 

When can I switch to a synthetic oil on my new or rebuilt engine?

For break in we recommend at at most 200-400 miles on a break-in oil like Driven BR or 607-7177 API CI-4 15w40 engine oil. This would be followed by the use of an intermediate conventional oil such as Driven HR or the aforementioned 607-7177 oil for the next 3,000 to 5,000 miles, before switching to a semi- or full-synthetic oil. For our Porsche customers, we recommend running Driven BR for the first 20-30 minutes to allow for camshaft/lifter/rocker break-in, to be immediately followed by an oil change to one of our recommended intermediate oils.

For Porsche models, once the engine has been completely broken in and the piston rings are fully seated, we recommend Driven DT50 (15w50) for aircooled engines. For watercooled engines, Driven DT40 (5w40) is recommended in place of a Porsche A40 approved oil. Driven FR50 is also suitable for those who would prefer to use a 5w50 viscosity in their watecooled Porsche engine. Porsche engines with direct injection should use Driven DI40 in place of a Porsche C40 approved oil.
 

Can I use an oil additive to increase the level of Zn and P in my engine oil?

Never use oil additives to boost ZDDP in your engine oil. Just use the right oil. All Driven Racing Oils are fully formulated to protect classic car and performance engines with the correct ratio of ZDDP, friction modifiers, and detergency. No further additives are necessary. Adding a ZDDP booster can throw off the balance of the additives in your oil and can actually cause harm to your engine. If your engine oil needs an additive, you are using the wrong oil.
 

Do I need to add a moly additive to my engine oil?

If you are using the right engine oil for your application, no additives should be required. Those concerned about Porsche Cylinder Bore Scoring should know that using an oil with high levels of moly is important to preventing cylinder bore scoring. Porsche A40 or C40 approved oils do not have sufficient levels, which may require supplementation with a product like Liqui-moly's MoS2 or Ceratec treatments. However, if using Driven DT40 or DI40 oils in your Porsche, no additive is required as these oils already have high levels of moly friction modifiers to help prevent Porsche cylinder bore scoring.
 

When should I carry out used oil analysis?

It is best to choose a motor oil and stick with that oil and have it tested using used oil analysis to determine a baseline for your engine. This ideally would start with testing of the break-in oil and every subsequent oil change. Through repeated sampling and testing at every oil change, used oil analysis gives you trend data to determine the condition of your engine. The initial sample from break-in should have the highest level of wear metals. Wear should decrease as the engine gets more time and mileage on it. If the wear levels start to trend back upwards or return to levels as high as the initial sample, you likely have a problem. In most cases, used oil analysis can identify issues before there are any actual symptoms. Used oil analysis also can be used to determine appropriate oil change intervals based on your driving habits and also to determine if the oil you are using is correct for your application. The key is regular testing – trending is required to identify problems before they become costly to repair or catastrophic.

The only lab we use and recommend is SPEEDiagnostix Used Oil Analysis.
 

When do I need to run a race oil in my engine?

Street oils typically protect only to 240F, even full synthetics. Anytime you do a high performance driving event, even if it’s your first time taking your car on track, you should use a true race oil. These oils typically have added anti-wear additives, reduced detergency, and improved anti-foaming additives, coupled with better base stocks that resist thinning at high temperatures. These oils are designed to protect your engine best under the stress of going on track. Remember, most race oils are good only for about 500 miles, so we recommend changing your oil immediately after a track day so you store your race car with clean oil. You should not store any engine with race oil as true race oils do not have the corrosion inhibitor, dispersant, and detergent additives street oils have. For street cars, that becomes a bit more complicated, requiring you to run change to a street oil between events and run the race oil only for track use. Remember, oil is cheap, engines are expensive! Driven XP Racing Oils are available in conventional, partial, and full synthetic in multiple viscosity grades for all applications.
 

What should I do if I have an older, higher mileage engine and want to use a synthetic motor oil?

Oils formulated from a group I, II, or III base stock (hydro-cracked petroleum product) are less prone to cause leaks or make existing leaks worse. Most semi or full synthetic oils are formulated with seal swelling agents to minimize leaks, so they often won't cause leaks in older engines, however if you have an existing leak, these oils likely will make those leaks worse. If you have an older engine that has never been run on a full synthetic oil, you might want to continue to use a conventional oil or try a semi-synthetic like Driven GP-1 over a full synthetic if considering changing oils.
 

Should I be worried about oil consumption?

It is common for Porsche engines with Nikasil cylinders to consume on average one (1) quart per 1000 miles. However this can vary depending on what oil is used and how the car is driven. In some cases, thinner oils or oils with high levels of friction modifiers can cause increased oil consumption. That said, all engines will consume some amount of oil during normal operation, and that amount can differ from engine to engine. If you engine suddenly begins to consume more oil than normal, that is something to be concerned about. Leaks are often the main cause for oil loss, however if you have no visible oil leaks, it can be assumed that you are burning the oil. The engine oil should be changed and filter cut open to be inspected for debris. Used oil analysis may help to determine if the increased oil consumption is a result of worn components or some external factor such as fuel dilution. A compression can help to identify the cylinder or cylinders that may be to blame just as a leakdown test can determine if the guides or piston rings are worn, both of which can cause increased oil consumption.
 

Should I use a non, partial –synthetic, or full-synthetic motor oil, or perhaps a motorcycle or diesel oil?

An oil's chemistry is more important than whether it is a conventional, partial, or full-synthetic, but all things equal, if you are using a properly formulated engine oil for your application, using a synthetic will provide the best protection. At the end of the day, the additional cost is a small expense to pay for the added protection.

Many years ago, diesel oils were an acceptable alternative to street car oils. Unfortunately, this ended with any diesel oils with the introduction of the API CJ-4 standard. Modern diesel engines have diesel particulate filters, requiring the engine oils to be reformulated to protect these emissions control devices. Motorcycle oils once considered suitable alternatives to street car oils because of their exceptional shear stability, oxidation and acid control, and high-temperature protection, have been reformulated, making them unsuitable for classic car and performance engines, including aircooled Porsche models.
 

What viscosity motor oil should I use?

You should always refer to your owner's manual for the recommended grade and viscosity of oil to be used in any engine. Typically bearing clearances will dictate the appropriate engine oil viscosity, so it is important to talk to your engine builder for their recommendation when selecting an oil for your rebuilt engine.

For most aircooled Porsche owners, a 15w50 or 20w50 can be used year round. For modern watercooled Porsche models, a 5w40 can be used year round over the factory recommended fill of Mobil 1 0w40. For Porsche models driven in colder climates, remember that below 15F (-10C), even on an aircooled Porsche engine, you probably should not be running a 20w50 or15w50. You should run a 5w40, which is good down to -13F (-25C) for cold starts. For comparison, a 0w40 is good down to -40F (-40C). If you plan on starting your watercooled Porsche engine at temperatures below -13F (-25C), you should consider running a 0w40 instead of a 5w40 on models where an A40 oil is recommended.
 

What engine oil or oil additives are best for Porsche cylinder bore scoring?

An engine oil formulated with high levels of moly will help extend the life of your Porsche engine. The inclusion of moly in the engine oil reduces Alusil and Lokasil cylinder wear. Unlike ZDDP that cannot bind to aluminum, moly can. Since the cylinder bores in engines with Alusil or Lokasil blocks are uncoated raw aluminum, moly is the only additive that can bind to the aluminum and exposed silicon particles and reduce cylinder bore wear. Coupled with increased oil viscosity of a 5w40 or 5w50 over a 0w40 oil, moly reduces friction while the increased film strength provides more cushion between the pistons, rings, and cylinders.

Driven's DT40, DI40, and FR50 oils are all formulated with a min of 300 ppm of moly for added Porsche cylinder bore scoring protection, so no additional oil additives are required.

If you are using a Porsche A40 approved oil, most have little to no moly, so using an additive like Liqui-moly Ceratec will boost moly levels and provide similar protection. However we still recommend using a fully formulated oil rather than relying on oil additives to boost wear protection.
 

What engine oil is best for my Porsche IMS bearing?

Whether or not you have replaced the Porsche IMS bearing in your Boxster or 911 996 engine, it is important to use the best oil possible in your Porsche engine. The aforementioned Driven DT40 oil has higher ZDDP anti-wear additives and high levels of moly friction modifiers, both which benefit the intermediate shaft bearing. Also using a 5w40 over a 0w40 engine oil viscosity will provide a higher HTHS viscosity, which in essence is a measure of the film strength. The problem with the factory recommended A40 oil is that it starts off thin and shears out of grade very quickly, resulting in a viscosity that is below the minimum recommended for lubricating a ball or roller bearing. A40 oils will have lower anti-wear and friction modifier levels, making these oils a poor choice for protecting and extending the life of the Porsche IMS bearing.
 

What makes modern motor oils not the best choice for aircooled Porsche, classic car, or performance engines?

Modern motor oil formulations are governed by automobile manufacturer requirements and corresponding API or ACEA standards (among other standard bodies). For example, Porsche now recommends 10,000 mi or one year oil change intervals on their newest water-cooled engines. But at one point, Porsche recommended as high as 2 years or 24,000 miles with other European manufacturers recommending even longer oil change intervals. These long oil change intervals resulted in damaged or failed engines due to sludge formation.  Increased detergent and dispersant levels were required to maintain engine cleanliness during extended oil change service intervals. As mentioned before, increased detergency requires higher levels of ZDDP to provide critical wear protection - something modern oils do not have.

Another consideration is that modern engine oils are designed to protect emissions control devices, which requires a reduction or elimination of ZDDP anti-wear additives.

Lastly, fuel economy is the primary motivator for development of new API standards for motor oils. CAFE, or corporate average fuel economy, will be mandated to meet 60 MPG by 2025. This requires the use of thinner and thinner oils, all of which trade off improvements in fuel economy at the expense of engine longevity and increased wear.

Modern oils are deficient in multiple respects to the oils previously available, making choosing an oil even more difficult and precarious for your older engine. Most importantly, these requirements mean modern oils are most certain death for older engines for which these oils were never designed or tested for use in.
 

Should I use an engine oil flush in my engine?

If you have an engine that is dirty or has sludge buildup, never use an oil flush product. We have seen many engine failures following the use of an engine flush product. Additives to clear up noisy or stuck lifters or engine flush products will dislodge deposits and plug oil passages, among other things.

The best way to clean a dirty engine is to pull the sump if possible to clean sludge or any other contaminants. The oil will need to be changed epeatedly, with no more than 500 miles between oil and filter changes, until the engine oil remains visibly clean after 500 miles. Using this procedure will slowly clean the engine. We would recommend fitting a FilterMag oil filter magnet and magnetic drain plug as well to the engine, if not already fitted. A fuel additive with PEA (poly-ether-amine) should be used at every fill up until the engine and fuel system cleanliness have been restored. However, if the engine is beyond the point of no return with heavy sludge formation or if there is any wear debris indicative of mechanical damage, an engine rebuild is your only recourse for corrective action.
 

How often should I change my oil?

For most street driven Porsche models, we recommend an oil change interval of 6 months or 5,000 miles.

Older aircooled models like the Porsche 356 should be limited to 3 months or 3,000 miles due to reduced oil system volume. Same goes for older aircooled VW models with the Type 1 and Type 4 engine.

Dedicated track cars should have their oil changed after every event and should be run with a race oil for maximum protection. Race cars should not be stored with a race oil as these oils typically are not formulated with detergents, dispersants, and corrosion inhibitors found in street oils. Mixed street/track use cars should run race oil at the track and have that oil changed out immediately after to a street oil. This may seem extreme, but oil is cheap and engines are expensive!

For classic car or performance engines, changing your oil ever 3 months or 3,000 miles or cutting the manufacturer's recommended oil change interval in half is a good starting point. Otherwise, used oil analysis is recommended to determine the correct oil change interval for your application.
 

If I drive my car in the winter, what steps can I take to protect my engine?

In colder climates, typically a 0w or 5w viscosity should be used if your car will see regular starts below freezing. For example, a 0w40 oil is good for cold starts to -40F (-40C) and a 5w40 is good to -13F (-25C). If you drive in the winter, and especially if you drive short distances, you should follow your vehicle manufacturer's severe service interval. For Porsche vehicles, we would recommend changing your oil every 3 months or 3,000 miles. As said previously, oil is cheap and engines are expensive, especially Porsche engines!

Do not ever let your engine idle excessively- this includes starting the car and letting it run to warm up for an extended period. Porsche recommends driving the car immediately after startup to warm up the engine rather than letting it idle, keeping RPMs and engine load down (no wide open throttle acceleration) until the engine is up to full operating temp. Please do remember that on a watercooled car, the coolant warms up faster than the engine oil, so if your car doesn't have an oil temperature gauge, just be mindful that it may take a few more minutes for the oil to warm up completely in very cold climates. Ideally, engine oil temperature should be at least 150F before the engine sees high RPM or high load, such as WOT conditions.
 

When should I change my oil if I put my car into storage for the winter?

Vehicles stored for winter should have their oil changed prior to being put into storage. Driven Storage Defender, Carb Defender, or Injector Defender should be used to stabilize the fuel and protect the fuel system. It is important to add the additive before filling the gas tank and to run the vehicle to ensure the fuel with additive has made it completely through fuel system. After the car has been put into storage, do not start up and let your engine idle. It is best to let it sit dormant until you take the car out of storage and have the opportunity to drive the car for an extended period and get the oil to full operating temperature, ideally 220F to vapor off any moisture in the engine.

Adding a battery tender to maintain your battery and also inflating your tires to the maximum permissible pressure stated on the sidewall are added precautions you can take to make sure your car is ready in the spring when you want to pull it out of hibernation. Just don't forget to correct the tire pressures before driving your car!
 

What oil filter should I use?

Just like with motor oils, people have their favorite oil filters. We have purchased and cut apart dozens of brands of filters, all leading us to one conclusion - other than using a Genuine Porsche oil filter, the only aftermarket filters we use and recommend are Napa Gold filters. Napa Gold filters are manufactured by Wix who is now owned by Mann+Hummel who is an OEM for Porsche and many other German auto manufacturers. We do not recommend using the Napa Select or Napa Platinum filters.
 

Do I need to pre-fill my oil filter with oil before installing it on my engine?

We do not recommend pre-filling the filter with oil before installing it on your engine, however it is important to lubricate the o-ring or gasket on the oil filter to ensure the seal is not damaged during installation. Some will argue that you need to pre-fill the filter, however how would this be done on an engine where the filter is sideways or installed upside down. It obviously is not a problem having a "dry" oil filter on these models, so pre-filling your oil filter is not necessary or required.
 

What fuel system cleaner, lead additive, or octane booster should I use?

Fuel system cleaners are widely available from dozens of companies, all promising everything from helping you to pass emissions testing to increasing octane. Many do little more than put a drain on your wallet. In most cases, using a quality pump premium formulation is the best thing you can do for your engine, regardless of octane requirements. However, the only fuel additive that has any actual benefit is poly-ether-amine. PEA can be found in products advertised as a complete fuel system cleaner or treatment, such as Driven Injector Defender or Driven Carb Defender.

For fuel systems that have not been serviced properly or for which you do not have a service history, repeated treatment with Driven Injector or Carb Defender will be required to restore proper function. If you continue to have symptoms associated with bad injectors, the only solution will be to send the injector for cleaning or replace with new injectors.

If you have an older engine that does not have hardened valve seats and requires a lead substitute, Redline makes a products called just that, Lead Substitute, that also cleans your fuel system and is safe for injectors and catalytic converters. This product do not however provide protection from the damage of ethanol or should be used as a fuel stabilizer.

What fuel should I use in my car?

Most modern engines and fuel management systems can adjust for the increased octane and provide improved fuel economy and horsepower, so even though the octane requirement may be 87 or 91 octane, it can benefit from 93 octane. Most importantly, always use a Top Tier fuel. If an ethanol enriched fuel must be used, Shell's Top Tier V-Power premium unleaded is the fuel we recommend running, where available. Chevron with Techron is another excellent choice for Top Tier fuel. Where ethanol-free fuels are not available, do not use any fuel with ethanol content higher than 10%, as this will cause damage to fuel systems and engines not designed for higher ethanol content. Case in point, Porsche released a bulletin many years ago starting that Boxster and 996 models are compatible with E10 fuels, however prior models should not be run with ethanol content exceeding 5%, and recommend using the Porsche Classic Fuel Additive for these models. However, for most of the country, that's simply not feasible, meaning you need to use a fuel additive like Driven Injector Defender or Driven Carb Defender in these older models, or pretty much any car manufactured before model year 2000.

Stay away from 100LL aviation (AV) gas. If you need leaded fuel, use Redline Lead Substitute. Likewise, if you need to boost your octane, use race gas or a product like Driven Injector Defender+Booster.

Lastly, modern E10 fuels have a very short shelf life. Fuel not used within 4 weeks of being pumped will start going bad, so a fuel stabilizer must be added. Use of Driven Carb Defender, Storage Defender, or any other Driven fuel system product will stabilize these ethanol enriched fuels.
 

How much gear oil does my Porsche gearbox/transmission/differential take?

The approximate fill quantizes are as follows:

901 approx. 2.5 L
902 approx. 2.5 L
905 approx. 2.5 L
911 approx. 2.5 L
914 approx. 2.5 L
915 approx. 3.0 L / 3.1 L *with radiator coil
925 approx. 2.5 L
930 approx. 3.7 L
G50 approx. 3.6 L
G64 approx. 3.8 L
Front-axle final drive (four-wheel drive) Type 264/00 approx 1.2 L
Rear-axle final drive (Tiptronic transmission) approx 0.9 L
 

What is the difference between a GL-4 and a GL-5 gear oil and which one should I use?

GL-4 gear oils are typically recommended for synchromesh, spur, spiral bevel, and helical gears used in manual transmissions and transaxles and axles with hypoid gears operating under moderate speeds and loads without shock loading. GL-4 gear oils are considered safe for yellow metals such as brass synchros where GL-5 rated gear oils have a higher concentrated sulfur phosphorous that will attack yellow metals. GL-5 gear oils are typically recommended for hypoid gears in automotive axles operating under high-speed, high-load, and severe service conditions. For comparison, a GL5 gear oil has about twice as much extreme pressure EP additive as a GL4, ensuring the greatest protection, performance, and efficiency for a spiral bevel or hypoid gear system. A GL4 gear oil should not be used in a hypoid gear system as it can not only reduce performance, but also damage the gears. Although the GL-5 service rating technically supercedes the GL-4, that does not necessarily mean that a GL-5 will be satisfactory or appropriate for transmissions and transaxles where the manufacturer originally recommended a GL-4 gear oil.

A GL-5 can be used where a gear oil with the MIL-PRF-2105E specification is recommended, however not all GL-5 gear oils will meet the SAE J2360 specification that requires addition testing to above and beyond the API GL-5 standard.If you have an older engine that does not have hardened valve seats and requires a lead substitute, Redline makes a products called just that, Lead Substitute, that also cleans your fuel system and is safe for injectors and catalytic converters.

Driven Racing Oils offers GL4 and GL5 API rated gear oils, as well as Driven AT3 and Driven AT6 for automatic transmissions and Driven DCT fluid for dual clutch transmissions.

Want to learn more about modern oils and fuels and how they affect classic and performance cars, Porsches included?

Check out our past LN Engineering Tech Tuesday Newsletters on these topics and more:

How Does ZDDP and Moly Work in Your Engine

November 5, 2019

How does ZDDP and Moly work?

View (in new window)


Porsche Engine Oil Specifications and Recommendations

April 9, 2019

Porsche's latest changes to motor oil specification and recommendations.

View (in new window)


Lubricants and Your Porsche Engine

November 21, 2017

Lubricants and your Porsche® engine. 

View (in new window)


Modern Fuels and Your Classic or Performance Car

February 6, 2018

Modern fuels and your classic (or performance) car 

View (in new window)


Understanding Ethanol Fuels

November 26, 2018

Understanding Ethanol Fuels

View (in new window)


New Year, New You - SPEEDiagnostix Used Oil Analysis

January 22, 2019

New year, new tool. Used Oil Analysis by Speediagnostix.

View (in new window)

LN Engineering exclusively uses and recommends Driven Racing Oils for all Porsche engines.

SKU
Set Descending Direction

Grid List

48 per page

28 Item(s)

SKU
Set Descending Direction

Grid List

48 per page

28 Item(s)