I know that engine well as I work for Navistar, we could actually repair those engines compared to the EPA garbage on todays diesels. My techs are happy to get a non emissions engine repair when it is on the lot.

Energy One clutches recommend BM Trick Shift ATF in the primary and yes all of my Twinkie buddies use Syn3 in all 3 holes, Harley brainwashes them for warranty reasons and then complain about $12 a quart every time

 

I tried most of them ATF, synthetic, engine oil, and a couple I don't remember. I ended gonjng back to formula+. The difference between them for me is the feel letting the clutch. Some of them slip to much and then finally let the plates grab. Formula+ feel better as I let out the clutch.

Beary