Still working on getting it back on the rode. I topped off the transmission and let it idle in gear for a while up on the jack. The fluid turned to a nice chocolate milk color, so I assumed there was some water in there. I planned to change it a few times anyway after it had set for so long.

After the second change the fluid stays looking good. My Harley parts catalog doesn't say anything about fluids, the harley service manual tells me what "grade" of Harley-Davidson oil to use in the engine at what temperature range, but doesn't mention the transmission either, and finally my Haynes manual says that it holds 20-24 ounces and to use Harley-Davidson Super Premium or equivalent 20/50.

I used a cheap 20w50 for the flushes, but for actually riding it, is 20w50 heavy enough? I searched and saw everything from 90 to 140wt discussed but those were all for newer bikes/transmissions.

For those of you still reading or those who skipped to the bottom, the title pretty well sums up my question, what gear oil for the old 4 speed?

Thanks again for all your patience as I continue to learn how much I have to learn about getting this one back on the rode.
--Chris

 

I have always preferred HD Formula + in the transmission.

And your Shovel will be happy with any decent quality 20w50. I use Brad Penn 20w50 myself.

 

Shovels like anywhere from straight 50 to 70, depending on where you live
Very few take 20W-50
I've never had an issue with straight grade

 

I just filled mine with 50w

 

HD straight 60wt in the engine and Bel-Ray Gear Saver 85wt-140 for the transmission.

 

Valvoline has always been my preference for many years on a numerous application ,hasn't let me down ever.

 

Was recently reading about transmissions not needing the detergent in engine oil, transmissions are gears I like gear oil. 1 plus on Belray

 

the real deal is NO GL5 gear oil GL4 is hard to find -

GL5 eats the brass bushings in HI gear and first and second gears - before 1959 it eats the 3rd gear bushing

2 -- as well as the shifter selector main bushing for the hand shift or the ratchet top until 1978 when they changed the trans to turtle top

so in my shop we went back - and now use lucas 60 or 70 weight engine oil as it has lots of zinc in it

 

John are you saying you use that in the trans?

 

in all the old Harley going back to the 1936 first 4 speed and almost all the gearing and bushings in the unit is the same till 1977 small changes until 1984 in your FSM it tells you to use engine oil the same oil at that time of year you use in the engine

when the 5 speed came along it had NO bushings made of brass so the additives are for gear shear not life in brass -- different stuff