Ok, when does a speed master #4 actually take advantage of the rservoir can ? After oil is too hot or to maintain level in drive. From what I understand it is only if drive fluid is to hot and it needs to discharge ?

I was told it was for oil expansion. My mechanic said not to fill the reservoir. Fill the drive to the vent hole and call it good. With as much oil as they hold, when they heat up the oil has to have somewhere to go.

Jim

I heard the same thing. I think Im all good.

I fill my 3A's, and before, the 5's that I had on my boat, to the top "hole", then screw in the plug and continue filling until I see fluid in the bottom of the bottle. That way I know that they are full and if, after they cool, there is no fluid in the bottle, I need to check the drives for leakage.