Excellent Article on Oil...

[AZMerc39]

Originally Posted by Tim Ayers

Agreed. Curious of the logic of that.

Same. Why would you want to put a contaminated part back into your motor?

[paul2748]

This is an article posted by Ted Eaton who is an engine builder, specializing in Y Blocks. His take on diesel oil and ZDDP. He has a lengthier article on this subject which is too long to post here.


Diesel Oil and ZDDP
Use only oil rated for gasoline engines and not an engine oil rated only for diesel engines. The amount of detergent in diesel oil accelerates engine bearing wear on gasoline engines.

Depending upon the bearing clearances, I’ll use 10W-30 or 10W-40 oil for most stock type engine builds. I’m partial to the Valvoline brand but I’ve used others without issue. I’ll use conventional oil only for the break in and no synthetic or synthetic blend oil ever for engines with flat tappet camshafts like the Ford Y. The shear property of the oil is important so don’t use any oil with less than 30 in its viscosity designation on an engine with a flat tappet camshaft. When in doubt about the amount of ZDDP in a given oil, look up the manufacturers MSDS (material data safety sheet) and see what’s there. I prefer a minimum of 700-750 ppm of zinc phosphorus. A 4oz bottle of ZDDPlus supplements the first charge of oil just to insure that there is adequate ZDDP during that first run in period. With engines that leave this shop, I recommend the first oil and filter change at the 2000 mile mark. Changing the oil sooner than this can have you adding additional ZDDP additive that would not normally be needed after the 2000 mile mark.

As a side note to the ZDDP amount in the oil, an oil with reduced amounts of ZDDP simply means that the oil must be changed more frequently as the ZDDP does get used up over time. On the flip side of this, having too much zinc phosphorus in the oil can create a situation known as zinc overloading and over time, this will have the negative effect of accelerated wear or chipping of the cam lobe flanks. There is a balancing act here in having the right amount and not too much. New engines have a lot of metal to metal contact going on so having an additional amount of ZDDP during that break in time is okay.