As I said in another thread, STP makes the oils "stickier" so there is some lube on the bearing surfaces at startup. This is good on a car that sits for extended periods. I would NOT put MMO into an engine, except maybe a week before an oil change. MMO is terrific stuff, but it's a solvent and I don't want anything that may break down the oil's lubricating abilities. The fact that you notice that with oil, it's everyone has his own formula for success. Some of them are very wrong (Which ones? I dunno!) But the venerable Mod. As seem none the worse for it. Some guys run Walmart's bargain oil and some guys just can't pay enough for their oil. Remember, These cars were built at the start of the depression and called for an oil change every 500 Miles. Some of them may have actually gotten it! Then the war and the rationing. Again, how many were on the factory schedules, Not a whole heckuva lot. It probably was not until the late forties, early fifties that most of them saw anything like decent maintanence. The mod A is a tough little car! a real survivor!
Terry