How to change the outdrive gear fluid on your boat. Eddie first want you to get the proper tools for this project which include a flat screw driver, hammer, a slap hammer, the right fluid for your boat ( this can be found in the owner's manual), and pump to pump the fluid to the vent. Locate the drain in the motor and loosen it up with the slap hammer especially if it's tough to loosen. There is a seal that should be retained because it is very important. To speed up the fluid drainage you should open the vent to allow air flow. Once this is done you can open the engine compartment and lamp the hose. Once it's drained you should attach the pump to the drainage area and begin pumping about 2 and a quarter quarts of new oil into the motor. You should pump until it begins to come out of the top vent from the bottom up. Make sure you replace the seal because it is critical to this process. Check your gauges to make sure everything is correct and in running order and that it.