The old flat tappet camshaft and running a good
oil with the right
zinc and phospheros levels question, there has been a lot of posts on this subject, and I thought I had the situation sorted with running a diesel
oil a Chevron delo 400, which has good amounts of additives!
Then I read where high detergent diesel
oil have different additive packages, and high detergents which may cause problems with my CP Coated pistons etc, I find this hard to believe that a special coating on pistons etc would be affected by detergent in a diesel oil like Delo 400 which going by their tech sheet is good for petrol engines as well. Here is part of the article!
Can I use a diesel motor oil in a car?
Yes, but there is a catch. Many camshaft manufacturers recommend the use of diesel oils, many even name Shell Rotella T (CI-4 forumulation) as their preferred engine oil, along with some form of Zn and P additive, such as GM EOS. The only mention I have seen as to a reason not to use a diesel oil would be the lack of friction modifiers in diesel oils vs car oils or the fact that they may contain more of the Aryl ZDP rather than the Alkyl ZDP, but on the other side of the fence, usually friction modifiers are typically only used in very low viscosity motor oils that don't have the levels of Zn and P we are looking for.
The newest CJ-4 formulations are now limited in the amounts of Zn and P allowed, compared to the CI-4 forumations most users are familar with. I would recommend adding GM EOS to these newest CJ-4 oils as well because of this or keep to using CI-4 or CI-4 Plus oils instead. If the oil says CJ-4 even if it also lists CI-4 or CI-4+, more than likely it conforms to the new, lower levels. Thankfully, many petroleum companies have realized the need for two products, a separate CI-4 and a new CJ-4. Chevron Delo 400 is one such oil, easily found in most FLAPS. Just make sure to read the label!
Additionally, CI-4 diesel motor oils tend to have more detergents, and it has been determined in the SAE paper "Oil Development for Nascar" that overly detergent motor oils can block or "clean" the anti-wear films off of engine parts. Since low detergent packages increase the effectiveness of film formation, racing oils tend to have less agressive detergent packages, which is another reason many be to consider a racing oil versus a diesel oil for your engine.