75-90 Amsoil. I think any of the synthetic gear lubes are fine.

 

20w50 Amsoil in all three.

 

I'm running Mobil 1 V-twin synthetic 20w50 in all three holes . Bike shifts better and runs quieter than it ever did using three different Harley fluids .

 

75w140 in mine i believe it Amsoil. had 20w50 before and to tell the truth i have seen no real noticeable difference ...at 45000 miles now...

 

I run Spectro. Whatever you run make sure it's gear oil in the tranny.

 

in 02 h.d. stand on synthetic oil was that it's not rec. then in 03 or 04 out came syn 3 and it was good every where i think any lub that is changed as recomennded will work fine ive used mobil 1 75/95 , h.d. primary trans lub, syn 3 they all work....syn 3 in motor makes more tappet noise..

 

+1 Been using it for about 2 years now.

 

Had AMSOIL 75w140 and with the cold weather it seemed a little stiff, but it worked awesome last summer when it was over 100 degrees. Just did my oil change last week and went to AMSOIL 75w90 sever gear and not as stiff when it's cold out.

 

Lots of people are using the redline shockproof heavy. I read a lot about this and changed mine. There is no more clunk when putting it into first, I can find neutral a lot easier and no more whining when I drop down from 6th to 3rd or 2nd when coming to a stop. Do a forum search and read up on the reviews of this product. Best $12 you'll spend on tranny gear oil.

 

You are right and thats what I thought even though I posted it anyway. With over 9 pages of replies though, it seems it is a subject worth beating. It even got your attention and response...

Reading alot of people using Mobil 1. I have worked in the marine business as a tech for awhile. At most the marina's I have worked we have always used Mercruiser Dino oil in all makes with great success. Lots of boats out there with over 1000 hrs and no problems. The two boats I can remember,(both newer Mercruiser GM engines) where the owners insisted using Mobil 1 syn both ended up needing long blocks. Both isolated cases had scored cylinder walls. Both boats were well maintained with oil changes atleast every year if not twice.

I'm not saying that this means that Mobil 1 is going to blow your engine up but I personally think twice before running it myself. Out of the over 620 boats a year we serviced at that marina the two that had issues were the only two on Mobil 1?