I am no fan of running any brand of full synthetic lube in conjunction with a wet plate friction type clutch.

You all can laugh at me, but I run Yamaha 4R semi-synthetic 10W50 in my primary. If it protects 160hp, 10,500 rpm 1000cc crotch rocket engines, it's good enough for my low rpm, chug-chug primary system...

My primary functions perfectly smooth, and consistant, and my clutch action is smooth, and also bites hard and consistant as well when called upon to do a tire smokin' burnout...

 

Do not run gear oil in the primary. When cold, it will cause the clutch to drag. It may also cause slipping depending on the friction modifiers in the oil. Run the recommended viscosity oil or run ATF. Primary oil is more for cooling of the clutch than lubrication.