Don't shoot the messenger here. The June issue of American Rider has an article by Joe Minton on clutches. Minton says that ATF is fine for the clutch plates but a lousy lubricant for the gears and chain.

 

Does he say why? They've been using ATF in 4x4 transfer cases (chains & gears) for decades and it has worked exceptionally well. I don't use ATF in my primary, I'm just curious...

 

You don't need a fancy oil in the primary, it's not as "hostile" of an environment as the motor or transmission. Fromula+ works just fine.

 

I just re-read the article. He claims that what the chain and sprockets really need is gearbox or differential oil but they would obviously screw up the clutch plates. He recommends the HD Formula+.