Buyer Beware: Diesel Oil Has Changed

A lifter with excessive wear, possibly due to inadequate lubrication

If you use diesel engine oils in your car for their higher levels of anti-wear additives than found in off-the-shelf standard engine oils, it’s time to consider a change. The American Petroleum Institute has adopted two new heavy-duty engine oil categories that increase the importance of seeking out an engine oil containing the correct formulation of detergents and ZDDP for your application.

ZDDP, or Zinc dialkyldithiophosphate, is an anti-wear additive that has been reduced in all engine oils through the years to help extend catalytic converter life and lessen harmful emissions. The ZDDP reduction in gasoline engine oils particularly spelled trouble for older — think flat tappet camshafts — and high-performing engines, however, leading owners to opt for diesel engine oils that contain higher levels of the additive.

Certified Lubrication Specialist Lake Speed Jr. explains ZDDP creates a sacrificial film on contact points that acts as a wear surface in place of the metal. As ZDDP is reduced or more detergent is added, that film can decrease and component wear increase.

Substantial chemistry changes in the new diesel engine oil categories mean the widely accepted use of diesel engine oil plus ZDDP additive during the break-in process is now a riskier proposition than it was a few years ago.

“Diesel oils are becoming more specific to applications, and people using them off-label need to be aware,” says Certified Lubrication Specialist Lake Speed Jr.

The American Petroleum Institute’s new heavy-duty engine oil categories effectively eliminate backwards compatibility in the industry. CK-4 is the replacement for current diesel engine oil categories, while FA-4 is a new category altogether, created in response to updated greenhouse gas (GHG) emission standards affecting engines to be manufactured in 2017 and after.

Speed says owners should just steer clear of diesel engine oil in their gasoline engines and pay close attention to new labeling if using diesel engine oils in their towing vehicles.

“This really is risk management,” says Speed about the importance of protecting engines with the right oil, from the start. “Curveballs are being thrown here. So, buyer beware.”

He recommends during the break-in process owners turn to a ZDDP-enhanced oil rather than the new diesel engine oil options to improve surface mating and extend the durability of internal engine components in their new or rebuilt engine.

Driven Racing Oil offers break-in oil — actually a trio of products designed for different applications — as well as both synthetic and conventional oils specially formulated for street performance, hot rod, competition and race, and small and power sports engines.