Is It Ok To Use Full Synthetic Oil Such After Long Use Of Conversational Oil?

[imiceman44]

Unfortunately yes. And I like rabbit holes.

I tend to think on our older engines, clearances when new were less than they are now on more modern engines. That was one thing I didn't look at, what are the factory bearing clearances on the new engines? Does that align with some of what you read as justification?

As far as I'm concerned, the ability of an oil to remain on parts after shutdown is far more important than viscosity in startup. That's the only time the crank should be touching the bearing, and it seems likely that high quality and/or thicker oils will do much better at that. Oil pressure remains zero after startup for a period of time, worse after an engine sits for awhile. As far as I'm concerned, that's where oil performance is most important...whatever is left on the bearings is doing ALL the work of minimizing bearing wear, being able to move the oil faster (which I feel is of questionable importance in the grand scheme) due to viscosity seems a very minimal benefit.

GM spec'd 5W30 on the later 350's, I think that is as thin as I'd go, and no less than what GM ended up with on the 454 if the bearing clearances weren't changed. And I'd only run 5W-30 in the 350 to be able to run the same oil in my truck and car. Manufacturer recommends 5W-20 as the "primary" oil in my car, but 5W-30 is also "ok" per their recommendations.

I suspect all things being equal, keeping up on oil and filter changes at a proper interval is most important. Ignoring all the modern issues like converter fouling/lack of zinc, etc.

That's the technology Castrol magnatech is doing.
It's somehow sticking to parts after shut down and I would let it sit a week at a time and it would start like it was running a couple of hours earlier.

 

[MAXMAN]

wwwlelubricants.com . Possibly nothing better on the planet! Lots of documentation, and lots of testimonials from around the world. Been using/selling their products for about 15 years. Run their lubricants and additives in everything I own, and have tons of customer testimonials from tractors to ultra high performance race vehicles. My opinion only, do the research and make your own opinion based on that.