I read a few posts on this site about people using ATF in their Primary. We're talking Automatic Transmission Fluid, correct? Is that a wise thing to do? Where did that idea come from? I have a couple bottles of ATF in my garage that I've had for at least 2 maybe 3 years. Haven't used it yet in my truck and I'm wondering if I could use it in my Primary. Scared to though becauseI think you're supposed to use10W40, non friction type. Any comments?

 

Whenever I ran a wet primary on my Shovel, I always used ATF. Never had a problem and the clutch seemed to work better. I used it on my Evo until I installed a primary belt drive. The only caveat I can think of is the inner primary bearing on Evos, and I'm guessing on Twinkies, too, is not a sealed bearing as it was on the Shovels. Whether the ATF will properly lubricate the late style bearing is something I don't know.

 

Use Redline MTL. It is a 70w80 Group V synthetic gear oil that has a pour point like a 5w30 motor oil. It is GL4 rated for lubricating the open bearings and it has no moly friction modifier to effect the wet clutch plates. It is thin like ATF so it doesn't cause clutch drag when the bike is cold. I have been using it and really like it. It has been in service for this application in Harley's about 15 years. Costs about the same as Mobil1 Synthetic ATF. Check it out at www.redlineoil.com lots of guys use it.

 

Deer30048...I've been running that redline MTL in my 07 Ultra forseveral hundred miles now. Seems to be doing great.I decided to try it whenI switched over to that Redline Heavy in the transmission. Seems to havequietedthe transmissiondown a little bit...so far so good with both. I have one of those real loud noisey ones.Before switching to the MTL, I have always just used regular 20-50 in the primary on harley's.

 

Fox, I'm running Castrol GTX 20w50 (fossil) in the primary now. Did you notice any difference when you changed to MTL? FWIW, I changed to Royal Purple 85w140 in the tranny and it quietened most of the whine and clatter in 5th and all the clatter in 6th. It made a big difference. I'm getting quite a bit of noise (low-pitched whine) from the auto chain tensioner that I hear when idling but not when moving. Do you have this?