Any suggestions on an oil for a Sportster transmission/primary?

I need something that won't make the clutch drag and yet provides good lubrication for the transmission. I've been thinking of trying a quality ATF, like Mobil 1 or Toyota. Many automotive manual boxes use ATF, so it should hold up to the shear loads and still be good for the clutch plates. I've seen that someone used MT90 successfully, as well as another Redline gear oil. Maybe the same Mobil SHC630 I've been using in my bike. It doesn't have any friction modifiers, so it should be OK for the clutch.

I'm just not happy with Forumula + and they don't make Sport Trans anymore (and I finally used up all I had).

 

Mobil-1 75w90 Gear Oil for a Sporty.

 

Mobil1 vtwin 20/50 or Amsoil 20/50 will shift fine. I wouldn't use atf in the trans.

 

Use Amsoil 20W50 for everything on the Sporty's although second choice would be 75W90 like Charley ...

 

Myself and most that I know with Sportsters (including a couple of Harley dealership mechanics) run nothing but Mobil 1 synthetic 75W90 Gear Lube in the combination primary/tranny.

It has a API GL-5 rating, for heavy duty use in gears and differentials, and the moly ppm count is low enough that it won't cause any possible problems with the wet clutch.

No one I know has had any problems, and one Sportster (owned by a Harley mechanic) has been running the Mobil 1 75W90 for over 85,000 miles.

If you want to run a 'engine oil' in your transmission it's your choice, but I run gear lube, not engine oil in the manual transmissions on my cars and trucks, as well as the manual transmissions on my bikes.

And before anyone mentions 75W90 gear lube being 'too thick' you need to know that the viscosity (thickness) of engine oils and gear lubes are measured differently.

75W90 gear lube has about the same viscosity, or thickness, as 20W50 engine oil..

 

Thanks, guys. I'll pick up some M1 75W90. We have over 50K miles on the bike now, all but about 1K put on by my wife, and I just put a new clutch and primary chain in it. I won't go through the details, but let's just say I want to be extra careful with the clutch. I also am not comfortable putting engine oil in the transmission. I think the SHC 630 is a little too slipery for the clutch plates, but it works well in my 5 speed.

 

im not sure if i can mix them or if i should stick with one kind, i put 20/50 in the engine and wondering which to use in the tranny
any suggestions

 

[QUOTE=OldFenderGuy;5502499]Myself and most that I know with Sportsters (including a couple of Harley dealership mechanics) run nothing but Mobil 1 synthetic 75W90 Gear Lube in the combination primary/tranny.

It has a API GL-5 rating, for heavy duty use in gears and differentials, and the moly ppm count is low enough that it won't cause any possible problems with the wet clutch.

No one I know has had any problems, and one Sportster (owned by a Harley mechanic) has been running the Mobil 1 75W90 for over 85,000 miles.

If you want to run a 'engine oil' in your transmission it's your choice, but I run gear lube, not engine oil in the manual transmissions on my cars and trucks, as well as the manual transmissions on my bikes.

And before anyone mentions 75W90 gear lube being 'too thick' you need to know that the viscosity (thickness) of engine oils and gear lubes are measured differently.

75W90 gear lube has about the same viscosity, or thickness, as 20W50 engine oil..


For my 1996 1200 sporster I have used Red line 75W80 Primary cse gear oil. The specs on it is API Service Class GL-4 SAE Viscosity Grade (Gear Oil) 75W80 SAE Viscosity Grade (Motor Oil) 5W30. Fully Synthetic.

 

For my 1996 1200 sportster primary/trans fluids I have used Red line 75W80 Primary case gear oil. The specs on it is API Service Class GL-4 SAE Viscosity Grade (Gear Oil) 75W80 SAE Viscosity Grade (Motor Oil) 5W30. Fully Synthetic.

 

oil type is determined by gear cut, not all oils will perform well if used outside the intended lube specification.
hd sport oil is in the class of mobile one syn gear oils. if does make a diff between the weights, i use the heavier oil.
you did not mention the year, earlier sportsters used engine oil as they inter-mixed with the engine oil.