I think it is time to go over passenger car automotive engine oils in detail. I will be writing several articles to be published soon so I will try to get some of it out here. I feel this is a very general topic for all car owners on this board.
It’s criminal. Folk spend fortunes putting together super-sonic motors, only to skimp on the oil they use. Why? Oil’s oil right? Wrong. Even if it’s a standard engine, it deserves TLC considering it's extremely hostile working environment.
The correct running temperature of the oil is perhaps even more important than the water/coolant temperatures - so let us consider how to control them. Mainly because it seems to be the most misunderstood of the whole process, and oil cooler fitment almost a reflex when over-heating occurs where a tuned engine of any type is concerned. And in many cases on standard production road cars for that matter.
About a year ago I read about the reduction of zinc dialkyl dithiophosphate (ZDDP) in the oils supplied with API approval that could affect sliding and high pressure (EP) friction in our cars. The reduction of these chemicals in supplied oils was based on the fact that phosphates reduce the effectiveness and eventually damage catalytic converters and introduce minute amounts of pollutants into our atmosphere.