Laughing. So now we've got instructions from Rivera to use:
1. Type F ATF,
2. Dexron Type III ATF, and
3. Synthetic 20w-50 motor oil.

All of which will probably work just fine.

 

I called them and they recommended ATF which I used, when I talked to the owner in Sturgis and he said he didn't like it on the newer bikes because ATF doesn't lube the compensator enough and that with the trouble people have with them going bad the 20W50 would be a better lube for it and still work with the clutch

 

I run atf type f in my twincam primary, I change it more often than the other fluids simply because of the heat issue. In you car the ATF fluid is cooled by the radiator and in some cases an auxiliary trans cooler. As for lubrication of the chain and bearings, transmissions have bearings and in some instances (AWD) there are chains. The Viscosity of ATF is around 7.3 depending on the maker.
I also use Mercon ATF in my Fork tubes 7.3 is the viscosity of HD fork oil.
In my trans I use 75-90 weight gear oil, it is a transmission not an engine.
Clutch packs, chains and bearings = ATF
Gears and shifting forks riding on
bearing shafts = gear oil (I use synthetic)
Pistons, rods, crank pin,
valve train and so on = Motor oil
buying fluids from HD by HD = mo money.

 

For what it's worth I have been running a Rivera Pro-Clutch in my 08 RK for a little over 72,000 miles. All of which have been done using Red Line Primary fluid. First with the stock clutch basket assembly with their silver spring and on my current build using their Pro-Clutch with the complete clutch basket and TPP Variable Pressure Plate assembly.

They do recommend ATF but when I called them directly expressing my concerns over proper compensator lubrication (I was on my third HD compensator) they told me to go ahead and keep using the Red Line. The ATF is all about proper friction and making their clutch operate optimally. I’m sure it does optimize their clutch performance but I was skeptical about the lubrication of the compensator. Their Pro Clutch, when adjusted properly, will work flawlessly with any good Primary fluid. I can’t speak for regular motor oil as I have never run it in my Primary.

I'm currently running a Baker Comp and Baker Armored Attitude Adjuster with the Pro-Clutch, putting out a little over 110 HP and 125 ft-lb of torque. I have had zero issues with clutch slippage, grabbing or harshness using the Redline Primary Fluid.

This is how they should come from the Factory

 

http://riveraprimoinc.com/html/faq.html
I would use what Rivera/Primo specs out in there instructions. If you have problems, the 1st thing they will ask you, is "what type of fluid are you using in your primary" ?