I am laughing in reading some of the replies in this thread. Not laughing at the folk who posted, but thinking about my mother who passed away at age 92 a few years back and her idea of when to change oil in a car.
She had held onto my brother's Thunderbird after he passed away. It was an 80's model (I don't recall what year though), in which had less than a thousand miles on it when he had died. Never in her life had she ever changed oil in any vehicle she owned and this one was not treated any different by her. She simply went out into her garage and checked the level on the dip stick. If it was near or below the line on the stick, then she simply added oil to bring it up to the proper level. Nothing more and no change what so ever. Year after year after year she did this and never an actual oil change, but just topping the oil level off, instead.
When my Mom passed away my sister and her hubby took the car back to Indy from Temple, Tx. He tore into the engine to restore the car and to his amazement, the engine was as clean as a whistle. He absolutely could not believe it as he was aware of how Mom did any service to the car. The car had near 100,000 miles on it from Mom driving the wheels off of it while she owned it and she was no a careful driver by any means. He is a retired Chrysler worker who worked in the deburring area for their engines for quite a bit of his work life with the company, so he definitely knows engine wear and what to expect when an engine is treated like Mom had done to this car for all those years of not really changing oil.
I laugh at myself in looking over my new to me, 1930 pickup, as I have no idea as to how often or how well the previous owner had done oil changes, let alone lube jobs to any of the rest of the truck. In all my years of looking over various Model A websites, as well as motorcycle sites, I guess all the oil threads I have seen could not really top my Mom's method of servicing her own cars as to what works and what does not. It brings back some memories in how odd and different things can be when it comes to oil threads.
I have to wonder how many years my Mom could have gotten out of my pickup if she had owned it and done it as she typically did her other cars?