I have a 1972 HD/Aermacchi Rapido, in the service manual it calls for "HD Two-Cycle Oil" to be used in the transmission. I know that two-stroke oils have gotten thinner since then and I am wondering what oil I should use in it. While I'm on the topic, does anyone know what fuel I should be using? It calls for 25:1 using leaded regular. What should I use in its stead, as the 25:1 unleaded mixture runs like crap.

 

2 stroke oil in the transmission?

Back then, 30 wt or even 10w40 was very common in a wet clutch 2 stroke

 

yup. I was quite confused when I read it, but that’s what it said.

 

In the 70's we ran 30w non detergent for two stroke oil.

 

I know some 2 stroke dirt bike back in the day use automatic trans fluid in their transmissions. Someone out there knows the right answer and i would wait for it.

 

when in doubt, do as the factory did. actually, two cycle oil has improved greatly from back when. using regular engine oil will lead to a carboned exhaust port, which was a common issue even back then and the machine WILL run poorly. pretty sure the moco suggested the same oil so as to lessen confusion and getting the wrong oil being used.