In this video and article, we’ll walk you through the steps involved in changing the lower-unit oil on a sterndrive or outboard engine. If you’re not particularly handy or mechanically inclined, don’t fret, as the procedure is actually pretty simple—if a little messy.
Although the lower-unit gearcase oil (also called gearcase lube) should ideally be changed in the fall to make sure there’s no water in the gearcase, which could indicate a damaged seal, it can also be done in the spring for those procrastinators among you.
All you need is a screwdriver, a pan to catch the old oil, some paper towels or rags (lots if you’ve never done this before) and some fresh lower-unit oil. Check your engine’s maintenance manual for the exact type and amount of oil you’ll need then buy an extra quart in case you spill some.
(Note: Different manufacturers recommend specific types of oil for their engines, so make sure you buy the right kind.)