I have been around outboards for over 35 years. Old units like a 1973 135
hp Rude were first year designed with to small bearings on the crank. It
was fixed in 1974 to large bearings. Don't believe me check the crank part
numbers for the years and you will see. More oil in the 73 135 HP is my
advice and also to run Premium gas. No matter what anyone says premium fuel
has more cleaners in it to prevent the dreaded ring sticking in 2 strokes.
ALSO use only synthetic oil and the best you can get is Red Line . Why you
ask? It is simple.Synthetic does not leave deposits in the engine to start
with.