Hi All 

I am about to do a service 

I will be using motul twin syn 20 -50 , what do you guys use in the primary ? stupid hd doesnt state what viscosity it is on the formula plus bottle .

tried doing a seach but the search function on this site is not good.

thanks for your help

Thanks hilly .

I've tried a few, the HD stuff is OK but for shift quality this has been the best I've found, well priced too.

http://www.belray.com/sport-transmission-fluid

I have been wondering about the same thing. Redline have V-Twin Primary Chaincase Oil that they say is good for your primary, but would it be any good for a sporty? The same mob also have 80w gear oil that they say is good for sporties transmission and wet clutch.
I use their heavy shockproof in the fatty so thought I would look at their oil for the sportster too.
Anymore ideas out there?
Cheers.
Bucky

Redline recommend their lightweight shockproof gear oil for Sporties.  I've used it for about 8 years now without a problem.  Shifts well and no noise.

Tmode.

If you use Redline in a SPORTSTER PRIMARY, use only Redline MT. I used & loved the Redline Heavy shockproof gear oil in my Big Twin TC & ATF TypeF in the primary. But with the Sportster the primary & gearbox share the one oil, i would not use Redline shockproof oil in primary!!!!! I run Redline MT in my old Carb Buell 100,000k up been useing the redline MT for the last 15,000k & can feel diference, have used the old sportster gear box primary ( no longer avadable ) used Formula+ , used ATF TypeF used Penrite gear oil. & this Redline MT the best as it is from 0W to 90W, so there is no drag on clutch & riding in 40c to below 10c. both clutch operation & feel & gear shift beautiful.  but use what you like i don't make anything out of it. free advice.side note, some sugest the formula+ specialy made for the job, so if your useing it & happy or under warranty stay with it, the redline MT works good for me but it's not magic, just lubrication. Redline recomened it for sportster when i checked. i use Redline in motor too but $$$$ ( like perfume on a pig? )