I'm switching to Amsoil and was curious as to run the 20-50 Oil or 75-90 severe Gear in the tranny, and reasons for one or the other?

Thanks
Aaron

 

Severe gear in tranny.The gear lube is designed for shearing more than the engine oil.The 20-50 wouldbe too "thin"for the shock load of the tranny as well.Toby

 

Keep the 20w50 out of the transmission....it has no business in there at all. Use gear lube no matter what and accept no substitutes.

 

The lubrication needs of the gears is minimal and considering the relatively light loading experienced in this application, can be easily handled by a fluid meeting API GL-1 performance requirements.

Extreme pressure additized fluid such as those meeting API GL-4 or 5 are not required and as for gear protection, will not provide any significant benefit over a properly formulated GL-1 fluid. Indeed high EP fluids can be used in Harleys with the exception being a V-Rod in which the transmission and clutch share the same fluid. The benefit tends to come from the products viscosity rather than their EP treat level.

I Haven't see much of a difference between an SAE 50 motor oil and an SAE 90 EP gear lube. One would not expect much of a difference as both are similar in viscosity. When you go to an SAE 140 EP gear lube, the heavier viscosity tends to quite things down and smooth operation.

As for the use of an ATF fluid in the primary, we are currently not recommending it. The only reason is that it is significantly lighter than what is recommended by Harley. Going from a 17cSt fluid to a 7cSt fluid is just way to big a difference.

The Above is from AMSOIL R&D

Bear

 

Severe duty trans oil is all my shop will use, they wont even put the 20-50 stuff in.

 

If you wouldn't put Gear Oil in your engine. why would you consider putting Engine Oil in your gear box? They are 2 different oils, formulated for 2 different environments. FYI - HD has now backed away from the "one oil in all holes" gimmick.

In short, engine oil has additives to deal with the byproducts of the combustion process. Gear oils contain additives to deal with molecular sheering that occurs in the gear box.

 

Gear oil for the trans. I have tried both and the 20w50 is noisy compared to the gear oil.

 

Severe gear in tranny.The gear lube is designed for shearing more than the engine oil.The 20-50 wouldbe too "thin"for the shock load of the tranny as well.Toby

20/50 motor oil is the same viscosity as 80/90 gear oil.

http://www.maximausa.com/technical/l...s/spring98.pdf

FYI - HD has now backed away from the "one oil in all holes" gimmick.

Totally untrue statement. See any parts manual or the latest issue of the Enthusiest magazine, or any Syn3 oil bottle or brochure.

 

Check out the oil properties as listed on the amsoil web page for the 20-50 mcv and the 80-90 gear lube.The kinematic viscosity at 100 c. and 40 c.between the two are not even close to being the "same'.And the viscosity index between the two are 153 and 132 respectively.So,are you ready to run 80-90 in "your" motor?You`ll never find gear oil in mine.But, since you are so sure of it you`ve probably been running it for years-Correct! I`d like to see your dyno #`s.If you could start it that is.T