Ok for those of you who have rebuilt engines with moly rings... I am just getting around to finishing up my 351w rebuild and going to be breaking in soon. I read a post from 2000-2001 where the debate was whether or not to use synthetic when breaking in an engine. I did use moly rings, flat pistons (compression 9.1-1), and comp cam flat tappet cam in my rebuild. Just wondering what to use for break in oil??? Was thinking of using Royal Purple "Break-in Oil" but that would be pretty pricey for 5 qts! From what I understand Moly rings can be a pain in the **** to seat... So any suggestions to seat them would be great!

 

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

Change the oil soon the first time you run it. Use cheap dino oil for the first couple oil changes. I'd change it after 50 miles and then again at 500, then normal changes after that.

 

With the flat tappet cam, be sure to use a break-in oil with a good amount of ZDDP (zinc & phosphorous) to keep the lobes from wearing prematurely. Once the cam is broken in, I think it's fine to switch to synthetic. Most diesel oils have elevated levels of ZDDP.