Can anyone tell me what is the correct oil for the transmission and the final drives on a 1959 HD6E. I have heard all sorts of different grades from 80-90wt gear oil, 30wt motor oil, 85-140 gear oil.
I think it would be 80-90 gear oil. I had one of these years ago and I believe that's what I put in it. FWD
Thanks FWD , Have you ever heard of running 50wt. motor oil in transmission??
50 wt engine oil is the same consistency as 90 weight gear oil. I believe 50 weight would not have the additives of GL5 gear oil. There is also a GL1 gear oil that is what some say a mineral oil. Some of the old transmissions and heavy truck transmissions call for a 50 wt engine oil or GL1 gear oil. FWD