Just to change the subject a little.

I just finished re-assembling a 6.4 (essentially two 3.2's) that had been running mostly Redline and Motul at between 70 and 80-1. Had the guy that did the crash repair put the heads on right I would have never looked inside the heads. After a few years of running they looked real good, as did the pistons. Very little residual carbon on the combustion dome and no marring of the piston machining marks, so no cylinder contact. No carbon blow by either. Good enough not to change.