ZDDP & motor oil

[Steve V.]

This link is to the ZDDP web site with several tech briefs about using their product in regular motor oil instead of diesel oil in older engines.

http://www.zddplus.com/

Steve

[Adam S.]

Re: ZDDP & motor oil

Steve imformative artical, my buddy uses it in his 69 camaro big block , but he only uses half a bottle for every oil change, he said as explained to him this stuff zddp attaches to all the interia of motor parts & it would be over kill to use the whole bottle every time. He knows someone at Shell oil plant here in LA. at refinery & was told you really only need a small amount after the first treatment. I am sticking with Shell Rotella T, its seams to work for now. If they take all the zddp out of the the CJ-4 oils I will go with this for sure! To each he own.

[Duke W.]

Re: ZDDP & motor oil

Here's a link to an abstract of the referenced (3) technical paper:

http://onlinelibrary.wiley.com/doi/1...10405/abstract

I'm sure all you tribologists can draw your own conclusion.

BTW, note that this paper is 22 years old - published back in the day when S and C-category oil formulations were virtually identical, and most were dual rated carrying both the then-current S and C-category ratings, and the decision to market an engine oil product to spark or diesel engine owners was primarily a marketing consideration.

Vintage engines were designed to use higher oil viscosity grades than modern engines. Look at your owner's manual. I go by what is recommended in my Cosworth Vega owner's manual since some of the higher viscosity mulitgrades were not available in the fifites and sixties.

It states that straight SAE 30 is okay for cold starts down to 40 deg. F.; 10W-30 and 10W-40 are okay for ambient temperatures from zero to 100+ and 20W-50 is suitable for 20F to 100+.

Given the typical cold start and ambient temperature range that most of use drive our vintage cars in, 15W-40 is just about perfect.

Duke