Mar 04, 2025

• What is the best motor oil for my Porsche?
• Why is SPEEDiagnostix Used Oil Analysis different (and better) than others?
• Important update on oil filters

With spring officially only being about two weeks away, now is the time to get your oil changed. Still to this day, there is some confusion on what oil should be run and when.

• For air-cooled models, we recommend Driven DT50 for the street, where a 15w50 or 20w50 would normally be used.
• For water-cooled models where a Porsche A40 oil is specified, Driven DT40 should be used.
• Where a C40 oil is requireed, Driven DI40 can be used.

Both DT40 and DI40 oils are suitable where a 0w40, 5w40, 10w40, or 15w40 would be typically used.

Regardless of Porsche model, for most owners, changing your oil every 6 months or 5,000 miles, whichever comes first, is recommended, unless used oil analysis says otherwise for how your car is driven. If you do store your car for the winter, hopefully you changed it before it went into storage. If that’s the case, there is no need to change it when you pull it out of storage – you should be good for the season.

Unlike C40 oils which aren’t backwards compatible with A40 oils, Driven DI40 can be used in place of DT40.

DI oils are slightly more expensive due to formulation differences that make it suitable for occasional autocross of track use. However, we still recommend using a true race oil for track use, but these oils are only good for up to 500 miles (basically one track weekend) and you should never store your car with race oil in it, especially after it has been run. Race oils should not be run on the street due to lack of dispersants, detergents, and corrosion inhibitors needed to make these oils suitable for street use.

There is also some confusion on which race oil should be run. Flat 6 Innovations has always recommended Driven XP6 15w50 for M96/M97 engines that will see track use.

This is a must if your sustained oil temperatures exceed 225F or intermittently over 240F.

If you would like to learn more about engine oils, we’ve recently updated our Oil FAQ, so be sure to check out it out to learn the recommended oil for your application and everything else lubrication related.

As everyone knows, we work closely with Lake Speed Jr. and SPEEDiagnostix to offer precision used oil analysis to our customers.If you don’t already have your used engine oil tested, there are many reasons you should. Here are ten reasons why we recommend used oil analysis: 

1. Predictive Maintenance: Used oil analysis helps predict engine wear and potential failures before they happen, allowing for timely maintenance and repairs.
2. Extend Oil Change Intervals: By testing used oil, you can determine if the oil still meets the engine’s lubrication requirements, potentially extending the interval between oil changes and saving money.
3. Engine Health Monitoring: Regular oil testing provides insights into the condition of your engine by detecting metals and contaminants that indicate wear and tear.
4. Cost Efficiency: Identifying small problems through oil analysis can prevent costly repairs and downtime in the future.
5. Environmental Benefits: Extending oil life through analysis reduces waste oil disposal, benefiting the environment.
6. Warranty Compliance: Ensures compliance with engine warranty requirements by documenting proper maintenance.
7. Optimize Performance: Helps maintain engine performance by ensuring that the oil is functioning properly to lubricate and protect engine components.
8. Safety Assurance: Early detection of issues like coolant leaks or excessive wear materials in the oil can prevent catastrophic engine failures and increase vehicle safety.
9. Resale Value: Regular maintenance records, including oil analysis reports, can enhance the resale value of the vehicle by proving it has been well-maintained.
10. Customized Analysis: SPEEDiagnostix Used Oil Testing is tailored to provide more relevant and detailed information than standard checks. This last one is what makes SPEEDiagnostix different from the other guys.

Yes, SPEEDiagnostix does cost more. But there are valid reasons for this:

• Specialization in Performance Engines: SPEEDiagnostix focuses specifically on high-performance and racing engines, providing insights tailored to the unique demands of these engines.
• Comprehensive Test Panels: Offers more extensive testing panels you would have to normally pay extra for that cover a wider range of wear metals, additives, and contaminants compared to standard labs, which often focus on more basic analysis.
• Faster Turnaround Times: SPEEDiagnostix typically provides results faster than many other labs, which is crucial for racing teams and individuals who need quick decisions about engine maintenance and adjustments.
• Detailed Reporting: In addition to historical data, reports from SPEEDiagnostix often include more detailed interpretations and recommendations tailored to the specific needs of high-performance engine users, whereas other labs may provide more generic advice.
• Advanced Analytical Tools: Utilizes state-of-the-art technology and testing equipment that can detect finer particles and subtler variations in oil composition, offering a more precise diagnosis. This includes using the more accurate RDE method with twice the resolution, compared to other labs that use the ICP method and separate FTIR and GC tests not included in standard testing by other labs.
• Expert Consultations: Provides access to THE expert in engine oil analysis who can offer detailed explanations and actionable advice based on the analysis results, which you’re not getting from a standard lab. Lake Speed Jr. is a Certified Lubrication Specialist and Oil Analyst.
• Industry Reputation: SPEEDiagnostix is often recognized and respected in the motorsport industry for its precision and reliability, making it a trusted partner for serious competitors and enthusiasts.

For those familiar with used oil analysis, SPEEDiagnostix does not offer TBN testing. TBN is an outdated test method developed for high sulfur diesel fuels. Today's low sulfur fuels make TBN an irrelevant test. Major OEM’s like Cummins and GM stopped using TBN as part of their analysis program nearly 10 years ago. FTIR is the modern way to determine the useful life of the oil and is the method SPEEDiagnostix utilizes.

Optional particle count testing is also now offered, which makes checking for IMS bearing wear with used oil analysis possible, whereas this isn’t the case with normal used oil analysis testing that can’t see particles that are large enough to see with your eyes.

As always, shipping is free on all SDX oil testing kits and all kits include pre-paid shipping for sending your sample to the lab.

NOTICE:

Often Porsche owners will send us their results from other labs and ask for us to review them and to make recommendations. Due to the large number or requests we receive, moving forward we will only discuss UOA results from paying customers who have purchased their used oil analysis directly from LN Engineering.

Important Update on Oil filters



As many are already aware, more and more manufacturers are off-shoring production. This includes Mahle, Napa, and other manufacturers having their filters made in China. With regards to Napa Gold filters, our supplier can no longer guarantee that they can supply only those Napa Gold filters that are made in the USA or Mexico, rather than China, so we they have opted to change to supplying genuine Wix branded filters. For those unfamiliar with Wix, they used to be the sole supplier to Napa for their Gold filter, and Wix is owned by Mann/Hummel, an OE for most European auto manufacturers. Rest assured, the Wix versions have not changed and they are exactly the same as the Napa units they are replacing, so when ordering your oil change kits or replacement filters from LN Engineering, you will get the right filter for your car.