Oil additive ?

[supertruck]

Everyone has their preferences. I use Amsoil Dominator in my 340 Dart and my mini-stock S10 circle track racer. No issues at all.

 

[Woody500]

I made Zinc Dialkyl Dithiophosphate (ZDDP and other acronyms) when I first joined Chevron's additive division in 1981. There are several types of ZDDP based on the alcohol group that makes up the hydrocarbon part of the additive. I can discuss this further if anyone is interested. ZDDP is a sacrificial additive that is depleted with age and is one major reason for changing oils (the more frequently, the better). But is also works by corroding the lifter and lobe surfaces forming Iron Sulfides and Phosphates that prevent destructive metal-to-metal contact of surface asperities.

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Wear occurs when the points of the asperities microweld to each other pilling apart the surface. ZDDP forms a film of sulfides and phosphates that do not microweld slowing down (considerably!) the normal wear process. But excessive amounts of additive are detrimental to this process causing faster wear, but still slower than if too little ZDDP is present.
As this additive is part of an overall additive package used to make finished engine oil, it is better to trust the oil formulator and company marketing the oil than it is to haphazardly using a top treatment additive. Yes, a ZDDP additive can help a modern oil protect slider follower camshafts from wear, but how do you know that what you added isn't causing other issues due to incompatibility with the existing additives in the oil. So I recommend using a name brand oil formulated for older engines over top-treating a product that may not be formulated for slider follower camshafts.

Could you pre-treat(corrode)lifter faces & cams with phosphoric acid(OS-PHO) to gain any of this protection?
Is that also why some camshafts were coated with a black, not necessarily smooth coating from the factory? Phosporic acid? Maybe some still are coated that way today?

 

[RLF Cuda]

Manganese phosphate is applied to steel for improved wear resistance. Specifically, engine parts, such as camshafts, gears, and piston rings, benefit from the coating’s protection, especially at performance break-ins. This protection is to prevent galling and control the wear of the moving parts.
https://finishingandcoating.com/index.php/conversion/1313-phosphate-coatings-some-basic-points#:~:text=Manganese phosphate is applied to steel for improved,and control the wear of the moving parts.