Real Quickie:
I read 20-50 for engine/primary and 75-90 for tranny.
Some posters say they put 20-50 Amsoil in ALL the holes.
This is quite a difference of opinion. It would make sense to put the heavier weight in the tranny.
Other's opinions??

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I am a believer of putting motor oil in the motor and gear oil in the tranny.

 

These are my opinions. I have run AMSOIL 20W50 in all three holes with out a bit of trouble or noticeable difference, for one whole season. I then went to a gear oil in the tranny. (By the way a 20W50 engine oil and a 75/90 gear oil are the same weight. Different scale used to measure the weights.) I have used 75/90/ 75/100/ and 75/140. The only noticeable difference between the gear oils and the engine oil was the 75/140. In any case you can certainly run AMSOIL 20W50 in all three holes with out a bit of trouble. If you are experiencing any gear whine, the 75/140 will take care of it.

You can run any combination without a bit of trouble.

Bear

 

I agree with Bear. If Harley felt the trans needed a heavy gear oil in it to function it would have left the factory with it. and the service manual would say to use it. there are people that will only change their motor oil and never have any trans problems. the Harley gearbox is a toy compared to truck transmissions that really need a heavy gear oil. most trans problems are cause by abuse, racing,and improper shifting, and clutches that need to be adjusted. some newer trans have a whine to them heavy oil might muffle that, but your not fixing anything.,,

 

I use any quality 85/90 gear oil from any auto store. Done that since 84..........all good so far

 

Since you have the 6 speed, look into getting the Spectro Severe Gear: http://www.spectro-oils.com/products...oducts=cruiser

It seems everyone that has dumped it down that trans hole swears by it, including myself!

Happy hunting!

Randy

 

+1 gear oil is more shear stable in a transmission application.