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 www.foreignpartspositively.com/.
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