Lycoming O-360-A4M

[MRC01]

This is a Penn Yan built to "new" limits, installed in my 1980 C-172. Oil use stabilized at less than 10 hours, but I continued following the break-in protocol up to 50 hours. Interestingly, it had high Al and Cr at first, and it's only now, approaching 400 hours, they're finally coming down. That's an unusually long time for break-in metals to stabilize. Engine runs great, strong power, full compressions, high efficiency.

I use the Camguard additive which is why the Ca and P are elevated.

 

[dnewton3]

The Cr wear rate seems to have dropped only a tiny bit, and the Al wear rate really hasn't changed much whatsoever. Overall, the typical "break-in" either isn't over yet, or really wasn't very elevated at all. I don't know enough about these engines to understand what the break-in cycle should present. Perhaps there's data preceding the point at 187 hours? That would help give some perspective. In no way am I saying this is bad; just that there's no real reason to conclude that the wear rates have substantially dropped from this limited data set.

Are these samples only, or do they represent OCIs?

What is the typical oil temp at steady cruising altitude?

 

[Brons2]

What is the oil used? Clearly just about completely ashless.