All about oil for street and autocross use | Articles

Is it okay to run a racing oil in my street car?

Stick with a passenger-car motor oil (PCMO) for a few reasons. First, some racing oils contain increased zinc, which can damage the catalytic converter. Second, racing oils typically have a lower total base number (TBN), which reflects the oil’s ability to neutralize acids from combustion. Oils with a lower TBN require more frequent changes, which wastes time and money in non-competition vehicles. Third, PCMOs are designed with fuel economy in mind–racing oils are not–so they will help you maximize fuel economy and save a little money at the pump.

–Len Groom, Technical Product Manager, Amsoil

Which is worse for my car: the wrong oil or dirty oil? In other words, if I get in a jam, which is the lesser of two evils?

Both scenarios are detrimental to the engine. Dirty, contaminated oil could raise or lower viscosity. The wrong oil may not have the proper additive package necessary for the needs of the given application.   

–Kenneth M. Tyger, Director/Technical Services, Penn Grade/PennGrade1 Lubricants

How can I determine exactly what percentage of a semi-synthetic oil is synthetic?

You can’t. Semi-synthetic is a marketing term and not a technical definition.

–Lake Speed Jr.,  Certified Lubrication Specialist, Driven Racing Oil

You can look for clues to help interpret which oils might be formulated with increased levels of synthetic-base oils. Visit the manufacturer’s website and look at the product data sheet or technical data sheet for its oils. In this document, look for “Typical Physical Characteristics” or “Typical Technical Properties.” This section provides a high-level peek into the base oils used in the formulation. There are two numbers to pay attention to:

Viscosity Index: Oils with a higher…