Re: Changing lower unit oil 150hp xr6
I just filled my 90 hp which uses the slightly smaller gearbox to yours and used between 20 and 22 ounces. The quart bottle with the pump at 32 oz. should be all that you need.
You pop the vent plug(s) and the drain plug. After draining is completed, screw in the fill tube at the drain plug and slowly fill (reduces bubbles) till oil comes out the front vent plug (if you have 2). I usually add a little more to wait for the bubbles to clear out. Screw in that plug and continue to fill till the aft vent vents oil in the same manner. Install that plug.
Then unscrew the tube and as quickly as you can (to reduce the amount of oil loss) insert the drain screw.
All new gaskets need to be used to ensure a water tight seal.
Doing the fill in this manner (by the book by the way) ensures that the cavity will be full and the vacuum created by the upper plugs being in place will reduce the amount of waste oil that is inevitable in getting the bottom sealed up.
Mark