Originally Posted by
Epstein
I've always done performance break-ins the hard way. On a motor with a fresh hone and new rings, I just let it idle and rev to 2-3k under no load for 30 minutes with 10W30 synth. Then change the oil (10W30 synth) and filter, and head out to the dyno to start doing low boost pulls. Compression and leakdown were always great. Made a ton of power. Never had any issues.
The explanation I was given by the person who taught me this was that you need to load up the hard rings so that they file against the fresh honed walls while they're roughest. Made sense to me.
Agreed, besides using synthetic initially. The additives in synthetic create a thicker film on the cylinder walls as opposed to mineral oil that allows a little metal to metal contact so that the rings contour to the cylinders and get rid of some hot spots. Also mineral oil does not contain detergents that swell the neoprene seals up, initially I like to let the seals set, make sure everything is fine, then throw in the synthetic.
I respect your experience/judgment and am not saying what you're doing is wrong, just would like to know why you choose to run synthetic initially.