Originally Posted by Lark
Working many years as an auto mechanic and engine rebuilder, many internal engine failures were due to infrequent oil changes. Collapsed lifters, worn cam lobes and bearings, worn rings and pistons, shot rod bearings, worn rockers and shafts, pushrods filled with sludge, valve guides, all due to oil breakdown, not oil level. Oil is a complex molecular chain and breaks down in use. That would be considered an "oil failure".
I've brought in many heads to machine shops that they called "Quaker State" specials due to sludge build-up. BTW Quaker State changed their additive package a long time ago and is a fine brand.
Art Rigsby
I'll defer to your actual experience on that. It seems a broader sense of "oil related failure" - beyond just the entire engine seizing - is more realistic.
A question along those same lines - I equate sludge with dino oils, and somehow have the impression synthetics would not sludge. I'm guessing that probably isn't true though. Is it?