I bought a new Ford F150 in October, 1990.(4.9L in-line 6cyl.) I change the oil/filter at 3,000 mile intervals-that has always been the only constant.Oil is always store brand Walmart/Kmart/Pepboys/7-11 or whatever is cheapest, as long as it is 10W-30.
Mileage is now >178K on the original engine, which burns no oil between changes, doesn't foul plugs, and has never ever been opened up.
I offer this tale as testimony to support the theory that "oil's oil."