Porsche's latest Technical Information bulletin,  Allocation of Approved Engine Oils (33/18) released in January 2019, introduced several notable changes including the addition of gas particulate filters to their newest sports car models and new recommendations for lubricants for both aircooled and watercooled models. Backwards compatibility of engine oils is no longer assumed or guaranteed, so choosing the right oil for your engine is more important than ever.
There are now four Porsche oil specifications. 

A40 oils cover 1984 and newer sports car models, but with the newest vehicles, the C40, C30, and C20 standards have been introduced. Most notably, these new "C" specification oils provide protection against LSPI, or low speed pre-ignition, and protect emissions control devices. The C30 and C20 standards are provided for shared VAG platform engines that call for 30 and 20-weight oils, with thinner oils used primarily for improved fuel economy.

Mobil 1 ESP X3 0w40 is formulated to meet the new C40 standard:

Modern gasoline direct injected (GDI) engines are prone to damage from LSPI, so oil standards like API SN+ and GM Dexos2 have been introduced to provide protection from detonation at low speeds and high loads. LSPI occurs when engine oil infiltrates the combustion chamber and combusts before the ignition event. Changes include reduction of calcium detergents and elimination of sodium detergents, as well as increased Moly and other friction modifiers. Likewise, modern low-SAPS oils are designed with reduced anti-wear additives, like ZDDP, which can shorten catalyst life, or plug after treatment particulate filters. It is interesting that this new standard and the corresponding Mobil 1 C40 specification oil provides protection for these particulate filters, as it has been determined that gasoline direction injection engine or gasoline compression engines produce particulate matter in their exhaust, soot, like diesel engines, which poses a potential environmental issue. Remember, diesel engines have been legislated away and become less common due to the soot particulate matter they produce, so particulate filters have been added to many engines, and they are coming to gasoline engines now including some Porsche models.

The introduction of Porsche Classic's own line of oils replaces Mobil 1 0w40 and other listed Porsche A40 approved oils as the recommended fill for 1984 and newer models. 

Likewise, the new C40 oil is not backwards compatible with engines requiring the A40 standard. Porsche now also considers the 986 and 996 as classics, so choosing the right oil for your Porsche is that much more confusing.
Regardless of your choice in oil, regular used oil analysis is the only way to know how well your choice of lubricant is protecting your engine.

LN Engineering and Flat 6 Innovations has partnered with SPEEDiagnostix to provide fast and accurate testing with application specific data collected over our 15 years of collaboration.
The current recommendation from Porsche for oils for sports car models is as follows:

356, 912, 914, 911 up to 2.7 liters
Porsche Classic 20w50
911, 964, 993
Porsche Classic 10w60
924, 944, 968, 928
Porsche Classic 10w50
986, 996
Porsche Classic 5w50
987, 997, 987.2, 997.2, 981, 991
Porsche A40
Excluded from this chart are the Macan, Cayenne, and Panamera models and models requiring C40, C30, and C20 specification oils. It is best to refer to your owner's manual for the correct viscosity and approval required for your model, especially if the vehicle is under warranty. The newest models with gasoline particulate filters require the "C" oils for emissions systems protection, however earlier sports car models that require an A40 oil have more choices, especially those out of warranty.
See LN Engineering's current recommendations for lubricants. Download our free oil guide

Get your free copy of our oil guide from LN Engineering's Dowload Library (PDF format)
986 AND 996 Models

What is important to most owners is wear protection rather than fuel economy.

Choosing a 5w40 over a 0w40 oil typically results in about a 10% increase in HTHS viscosity, which is a measure of film strength. However, increased HTHS viscosity also reduces fuel economy, so wear and fuel efficiency go hand in hand. Likewise, some oils are formulated as low-SAPS, with lower anti-wear additives, so an oil with increased ZDDP, such as a mid-SAPS oil, should result in lower wear with minimal effect in longevity of the catalytic converter.

As evidenced by the approval of a Classic 5w50 oil for the 986 and 996, having an A40 approval isn't the end all be all when it comes to selecting an oil for your watercooled Porsche with M96 engine. For those who must have an A40 rated oil, Motul 8100 X-Cess 5w40 has always been a safe choice.
LN Engineering and Flat 6 Innovations have worked closely with Driven Oils to develop the best oils for Porsche sport car models for almost 15 years, including Driven's own Boxster rolling test bed and data collected from hundreds of engines at LN and Flat 6.
Those concerned with reducing wear and willing to lose a bit of fuel economy can use the Driven's DT40 through 2008, including the 987 and 997.

Likewise, the Porsche Classic oil recommended for the 986 and 996 can be used on the 987 and 997 without concern as the engines share identical internals. Although Driven offers their FR50 5w50 that would work for the 986 and 996, DT40 is formulated to provide high temperature and high shear protection and remains our choice for these models.
DT40 is formulated to provide high temperature and high shear protection and remains our choice for 986 and 996 models.

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Those with model year 2009 and later engines with direct injection should use DI40 instead of DT40, as DI40 is formulated specifically to combat LSPI and oil thinning due to fuel dilution common to direct injected engines. Engines requiring a C40 oil can use DI40 and likewise, DI30 and DI20 are available in viscosity grades matching C30 and C20 oils, but Driven oils do not carry Porsche approval.

D I40 is formulated specifically to combat LSPI and oil thinning due to fuel dilution common to direct injected engines. 

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356, 912, 914, 911, 964, 993, 924, 944, 968, 928

Since the early 2000s, the changes to oil formulations have negatively impacted older engines, specially the aircooled models. 

It is great to see Porsche recognizing that modern engine oils, like the A40 specification oil, are no longer appropriate for legacy applications and offering us several viscosities depending on model. Older engines require higher levels of anti-wear additives and typically have larger internal clearances than modern engines, requiring higher viscosities.
Learn more about how oils have changed and how that affects you and your engine.

Get your free copy of our Motor oil commentary from LN Engineering's Dowload Library (PDF format)
Where once off the shelf oils could be easily purchased that provided adequate protection, we not have to turn to specialty lubricants to ensure older and high performance engines are protected. 

Simply choosing brands that worked in the past like Brad Penn and VR-1 may not be the best choice anymore as even these oils have been reformulated due to the elimination of the sodium based detergent packages common to both oils. As modern oils are reformulated to protect against LSPI and meet other demands of current production engines, legacy additive packages used in oils for classic engines must change as well.

Thankfully, there are still plenty of choices from specialty lubricant suppliers, like Driven. Driven DT50 was developed and tested in a partnership with LN Engineering and Aircooled Technology (Flat 6 Innovation's aircooled side of the house) for both flat tappet and overhead cam engines, specifically tailored to the stresses unique to an aircooled engine. DT50's 15w50 viscosity provides ideal protection and cold flow down to 10 degrees F, which most classic Porsche vehicles will never see. However, if you do live in a climate where you will see sub-zero starts and ambient air temperatures don't exceed 60F, DT40 will provide excellent cold start protection and the proper anti-wear additives to protect your classic.

Synthetic oils provide excellent heat transfer, flow characteristics, and perform better than conventional oils, however older engines that are prone to leak may be better suited to a conventional oil like Driven's GP or HR oils, which are also formulated for optimal wear protection.

Not only have modern oils changed, negatively affecting component health, but fuels also have a detrimental effect on fuel system components in models manufactured before the year 2000. 

For years, everyone has known that adding a fuel stabilizer in your fuel tank is a good idea if you put your car in storage, but most don't realize that modern E10 (10% ethanol fuels start going back in as little as a month. Ethanol is hygroscopic, meaning it absorbs water, which leads to fuel system corrosion. Likewise, ethanol enriched fuels aren't compatible with older vehicles, especially those with carburetors.
Learn more about ethanol in fuels.

Get your free copy of LN's white paper on ethanol fuels from LN Engineering's Download Library (PDF format)
In late 2018, realizing there was a real issue and concern with modern fuels in older vehicles, Porsche Classic released their fuel additive, designed to both stabilize fuels and also prevent corrosion associated with ethanol fuels, while cleaning your fuel system:

When adding a fuel system additive, it is best to add it before you add fuel to fully mix it and it is recommended that you run the engine long enough to ensure all fuel in the fuel lines, carbs, or injectors are fully treated. It is important to add the additive any time you plan on putting the car into storage, but equally important that an ethanol additive is used at every fill up when using E10 fuels in vehicles manufactured before year 2000. 

Driven offers its Carb Defender, based off the fuel additives used in South American markets that run ethanol concentrations up to 100% to combat the negative effects of ethanol in fuel systems, offers similar protection to Classic's fuel additive.
DRIVEN Carb Defender combats the negative effects of ethanol in fuel systems and works in vehicles with fuel injection, both port and direct. 

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Lastly, where ethanol free fuels are not available, Top Tier fuels should be used, as they provide increased detergency and are more stringently regulated with tougher standards for fuel quality.
In-depth guide on how ethanol fuels affect your classic or modern engine.

Get your free copy from LN Engineering's Download Library (PDF format)
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