I think I would use the manufactures recommended fluid and not worry about it.

 

Use the ATF fluid your plates will last longer. If you think about it the primary and an automatic tranny have the same things in them, bearings, friction plates/bands, and chains in front wheel drive cars.

 

Amsoil synthetic ATF here. Some like synthetic trick shift.

 

Put the Pro Clutch in almost 15000 miles ago and have not had any issues running the ATF. I do not use an expensive oil either. If there would have been issues, I am sure by know I would have run into them.

Think about it, all automotive transmissions have clutch paks and they survive just fine on ATF. The oil in the primary is primarily used to control heat with a side benenfit of lubrication.