What do you use and what are your thoughts.

I have tried cheap 80W90 and Redline Heavy Shockproof (75W90 with film strength of 250W). Surprisingly, the 80W90 was the more quiet of the two. It is difficult to tell whether or not the heavier oil helped the locker performance at all. In theory, the layer of thick oil between the driver and coupler would allow it to uncouple more easily so in theory the Redline should work better. I suppose the film isn't thick enough to make a difference.

That said, the oil is meant to protect the gears primarily, not quiet down a locker.

 

I am thinking of switching to a 80W140. As it will both protect the gears better and quiet the locker down. It will maybe even get smoother performance out of the locker.

 

i run 80w90 in mine.