Originally Posted By: bonnie john
hi eagle
clutch drag is more to do with too much oil in primary than the weight of oil ( in my experience of nearly 18 yrs of owning and maintaining my '92 fatboy )
just my 2 cents worth ...
I feel the same way but wasn't sure I wanted to throw another variable into the question. Clutch drag and finding neutral has a lot to do with fluid level in the primary. And if you read enough posts it becomes clear that some people don't know how to properly fill the primary. So when I read about clutch performance from different people and how from their "seat of the pants" evaluation Brand/type A is better than B I have to take it with a grain of salt unless there is evidence that the level was proper and consistent for the comparison. Inproper level is an easy mistake to make as the Evo and TC visual fill level is different and some people read that it takes xx ounces and they just dump it in without checking for proper level.
All that said, the primary fluid just has to have good wet clutch performance, not damage the stator, and take the heat. ATF is proven effective in this application and is maybe/probably superior to other options. HD Formula + works just fine as well. A lot of people go with alternatives recognizing that for most of us the primary is not a $10/Qt application (that's US $).