57 Fairline 292 y block engine oil

[Ford Blue blood]

Going to have to be contrary here.  Synthetic oil while produced from petroleum products is not necessarily conventional oil.  The base material is manufactured, not distilled as conventional motor oil is.  Yes, synthetic has most all the additives as conventional oils but they are centered on corrosion, detergents etc., not viscosity control.  The video link is pretty good  at explaining this.

https://www.roadandtrack.com/car-culture/a12007368/what-makes-synthetic-oil-better/

My Mustang specifies synthetic 5W-50, not a blend but fully synthetic.  The F150 5.0 recommends a Motorcraft blend 5W-20 but I used fully synthetic 5W-20 and never had an issue, even while towing a Featherlite with a 4000 lb. car on it to the top of the hill to My. Rushmore!

[hiball3985]

I don't think anyone was saying they are the same when in the bottle, only they both start as crude oil.

[Frankenstein57]

My collector cars don't see much action in the cold, when they start flinging salt, I park em till spring. I've had good luck with 10/30 conventional oil, zinc additive in the old cars. The local DPW's now pre treat the roads with liquid salt brine when snow is coming, I'll probably never own a new car, lol