Just doing a litle research on Redline Shockproof Heavy for my '07 6 speed. You indicated in a previous post you had used this product. Still using it? Continue to have good luck with it in that '07 6 speed?
My post was a copy of a member that had tested several, I have not yet put anything in my 07, but run heavy shockproof in our 02 classic and it does great. Have mine sitting on shelf waiting till I hit 1k on my new SG.
ORIGINAL: iclick
Frankly, I think any quality hypoid gear oil, synthetic or otherwise, will work fine in the HD tranny.
I agree with iclick... Swapped tranny end cover last week to a chrome one. Lost a little Formula+ and all I had was some really old (sealed container)Castrol Hypoid 75-90 gear oil sitting around to top it off with. What a difference!! Shifts like a freakin Jap bike now.. so smoooth. It never shifted bad, but it is so much nicer now with just that little bit I added. Will eventually swap out the formula+ stuff for something better when I get around to it.