You may be right to not choose synthetic, depending how often you change oil, what climate you live in, and what bearing tolerances you run. Synthetic is actually a Marketing term more than a description of the oil anyways. Most "synthetic" oils are far from synthesized PAO Basestocks like Customers seem to believe. Anyways heres my laymans description of why i believe people should run Schaeffers.
The benefit is actually not that it holds up better or worse as a lubricating film, it's more that its already prepared to fail before you put it in!
The measure of oil film integrity in extreme conditions in terms of "will my oil still hold a film in my bearings?" Is probably best guessed by comparing the HTHS viscosities and shear stability after testing. In that sense almost nothing beats a true ester of glycol base stock(not schaeffers). Where Schaeffers really shines is their "anti-wear additive", which is more or less microscopic softer sacrificial metal bits suspended in the oil that are there to take the hit and get squished when your bearings press through the oil film and would make contact.
Schaeffers pioneered the use of molybdenum as a consumable anti-wear additive, and they still use it better than anyone. Add in that they also utilize antimony in the same way (i havent seen another oil with moly and antimony) and have excellent detergency without being solvent and their base stocks are incredibly shear resistant, and you basically have the best real world performance possible for ~$15-25 a gallon depending which blend you want.
I'm not employed by them or affiliated, I have to pick mine up at a distributor like anyone else. I have a fancy schmancy college degree in this stuff, and I firmly believe this is a great product from one of the best companies in business. They spend $0 on advertising because they can convince engineers and farmers to buy into their products just based on their quality and reasonable cost.
Try some yourself and run used oil analysis if you don't believe me.