Reformulated Motor Oils and Your Flat-Tappet Engine

In an effort to reduce harmful emissions caused by the burning of engine oil, manufacturers have reduced or removed some oil additives that are essential to keeping older engines running. Flat-tappet engines common in older British cars as well as Volvos and some American engines are wearing cams and lifters at a remarkably high rate.

Opinions as to the cause of this phenomenon vary to some degree. However most agree that today’s oils are not formulated with flat-tappet engines in mind as they are no longer produced for by any major automobile manufacturer.

In the last two to three years, there has been a reduction in the amount of zinc dialkyl dithiophosphate (ZDDP) contained in motor oils recommended for use with gasoline engines. In flat-tappet engines, this additive protects lifters and cam lobes from premature damage due to heat and friction by acting as a sacrificial layer between the cam lobe and lifter.

There are a number of readily available solutions for the old car hobbyist. See the resources below to find out how you can protect your engine.

Keith Ansell, owner of Foreign Parts Positively a shop specializing in British cars and located in Brush Prairie, Washington has researched and written extensively on this topic. (Older British cars are nearly exclusively powered by flat-tappet engines.) His website, including contact information can be found at

Click the link below for an article from the June issue of Hot Rod Magazine regarding flat-tappet cams and reformulated oil.
Hot Rod Magazine Article


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