Well his 73 has no cats and it was a fairly common recomendation back then. There was this product called Marvel Mystery Oil, which looked like transmission fluid. They described it as an upper ring lublicant. I used to put it in occasionaly in my old 60's cars. How else are you goin to lubricate the upper ring except by going through the intake valve. I wouldent try it today with cats and O2 sensors but I really have no data to say good or bad.

John Roncallo