Oh for the good ol' days. In the fifties and sixties and probably on into the seventies, replacing one of the quarts of oil at oil change time with a quart of ATF was not totally uncommon. The idea was to add lots of detergent to the oil to keep the inside of the engine clean. Compared to todays modern oil/additive combinations, engine oil then was crude by comparison.
You're dear ol' Dad probably improved an engine at one time with this remedy. In the sixties, you could take the valve cover off a lot of engines and find the ugliest gunked up mess you can imagine. When you found this, it was usually an engine using Havoline or Amalie (when was the last time you saw Amalie oil?)
Because there were oils that allowed engines to get really gunked up, there were lots of opportunities for various remedies to clean them out.
Be thankful for dear ol' Dad and his experiences, but if you do have a gunked up engine in these days, step up your oil change intervals and make sure the engine is piping hot when you drain the oil.
Change oil hot and change oil often,
'84 Euro 240D, 523K miles
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