Engine Oil: what's best?

[leadfoot6]

There is some discussion, with evidence, at "Bob is the oil guy" about the potential for leaks after switching from "Dino"(dinosaur i.e mineral oil) to synthetic oil-

Recently:

That said, there's no one size fits all rule IMO..if the thought of switching over to a full syn scares you - don't switch. Maybe a nice middle ground for ya is a HiMi syn blend w/extra seal conditioners... there are UOA's in the sub forum of syn blends doing 6k+ mile oci's. Nothing wrong with that in my book...

https://www.bobistheoilguy.com/forum...ic#Post5207177

Some years ago:

My S10 had also been run on dino, mostly VWB, for it's whole life. At about 100k, I made the dumb decision to switch to M1 5w30. Within a few thousand miles, I had leaks from a number of places. Switched back to dino, and the leaks are virtually gone. I know most guys say switching to synthetic will not cause leaks on older vehicles, and I used to be one of those guys- I had done it on several other vehicles, until it happened to me... I'm done switching on vehicles with over 50k on them or more than about 5 years old.

https://www.bobistheoilguy.com/forum...Number=2177122

As pointed out in the first quote:

That said, there's no one size fits all rule IMO..

Not all engines are the same and,

"Oils aint oils, Sol".

I imagine "an observer" has a mechanic who has seen past evidence of such things happening.