Originally Posted By: mbacfp
I think the moral of the story is that 10w-30 will provide excellent results compared to 5w-40 synthetic within Ford's OCI. Extended OCI beyond the truck's oil change minder...then a synthetic should be in better shape going longer.
No truer words were typed.
I've never said that syns are always a waste.
But I certainly believe people waste lubes, both syns and dinos, because they never run any lube to anywhere close to a true condemnation point where the lube is reasonably fully utilized. I want to be clear; I'm not advocating using any fluid to a point where the EQUIPMENT is compromised. Just talking about using a fluid to a point where it's near the capability limit. OEM OCIs are generally so overly conservative that no fluid is ever close to any point of real condemnation. At some point it is likely that a dino lube will degrade to a point that a syn will usurp it. But none of us, and I mean none, ever run any lube to that point anyway.
I've run dino engine oils to 3x the OEM recommendations, and the UOAs were totally fine. There's no proof that a syn can do any "better" in a "normal" OCI. It just does not happen. People think that running a syn is "cheap insurance". But there's plenty of reserve capacity in a dino fluid. So just how much extra-extra-extra "insurance" do you really need? If a dino is 3x under-utilized in a normal OEM OCI, then a syn is probably WAY MORE under-utilized.
Using a dino to the OEM limit is a waste. Using a syn is a bigger one. With no reduction of wear for the extra cost.
The only way to REALLY know is to set reasonable condemnation limits for the wear metals, vis, contaminants, etc. Then run your lube up to that point. Then choose a different lube and see if the ROI is equal/greater to the cost differential. If so, it's the one to use. If not, it's cheaper to OCI more often with the lesser cost lube. It's not rocket science, but it somehow escapes most every person, mostly because of the gross bombardment of marketing hype we endure.