How to Change Yamaha F225 Lower Unit Oil

Neglecting to change the lube in your Yamaha outboard’s lower unit can lead to some unnecessary (and very expensive) chaos!

Even a small amount of water mixed in with the gearcase oil can wreak havoc inside the lower unit. Every outboard’s lower unit oil should be changed once after every 100 hours of use, or when storing the engine. Watch the video above and follow the steps below to change the lower unit oil on a Yamaha F225TXRC outboard.

NOTE: We worked on a Yamaha F225, but the process is the same or similar on most outboard makes and models.

Tools and Parts Needed – Yamaha F225 Gearcase Oil Change


  • Oil pump
  • Flathead screwdriver
  • Drain pan


Yamaha F225 outboard engine lower unit oil change

Changing Yamaha F225 Gearcase Lube

Step 1. Tilt the outboard to about 30-degrees, which puts the lower unit at an optimum angle draining the oil.

Step 2. Remove the oil vent screw and washer from the top right side of the lower unit. Next, inspect the washer for wear and replace it if necessary.

Yamaha F225 outboard gearcase oil change

Step 3. Put a drain pan under the lower unit, and remove the oil drain/fill screw and washer from the bottom of the gearcase. Inspect the washer for wear and replace it if necessary.

PRO TIP: You should replace the vent screw and drain/fill screw washers after every few oil changes, regardless of what condition they’re in.

Yamaha F225 lower unit oil change

Step 4. Drain out the old gearcase lube. 

NOTE: This takes several minutes because the oil is very viscous.

Step 5. Tilt the engine back down to the vertical after the oil has drained out.

Step 6. Attach an oil pump into a container of marine gearcase oil and slowly pump the new oil into the lower unit. Continue to add oil until it begins to overflow from the vent hole at the top of the lower unit.

Yamaha F225TXRC lower unit oil change

Step 7. Reinstall the vent screw and washer, then remove the oil pump adapter and reinstall the drain/fill screw and washer.

Step 8. Clean off any excess oil from the lower unit using contact/brake cleaner and you’re done. 

Yamaha outboard gearcase oil change service

PRO TIP: Polluting water with even the smallest amount of oil is a federal crime and carries a hefty fine, so make sure your gearcase is 100% clean after you’ve replaced the lube.



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