50 years ago I was flying control line on a dirty grass field. After a tip over landing we would rinse off our motors with fuel then fly the model again. We never stopped to carefully clean the dirt out of our motors. Needless to say, they lost compression quickly. We had a substance we called Molly . It was a grey colored oil. We would put 3-4 drops into the intake of a worn motor while running and the compression was magically restored. You could treat most motors 3 or 4 times before having to replace pistons and cylinders.
I have recently come upon 4 old Baby Bee .049 motors that have been abused and have little compression. If I could find that old "Moly" substance again, I would try it before buying repair parts, as the parts cost more than a whole new motor on EBay. Does anyone know anything about this "Molly" substance? Is it still available?