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How to Maintain Your Outboard Motor Gearbox, Including Gear Oil Change

May 25,2024 | FllickerMarine


Maintaining your outboard motor gearbox is crucial for ensuring the longevity and performance of your marine engine. Here's a step-by-step guide to help you keep your gearbox in top condition, including how to change the gear oil.


Step 1: Check the Gear Oil Level Regularly


Before you head out on the water, it's a good practice to check the gear oil level in your gearbox. Low oil levels can lead to increased friction and wear on the gears.


Step 2: Inspect for Leaks


Regularly inspect your gearbox for any signs of oil leaks. Leaks can occur from the seals and could indicate that they need replacing.


Step 3: Drain Old Gear Oil


To change the gear oil, locate the drain plug at the bottom of the gearbox and remove it to allow the old oil to flow out. Be sure to capture the used oil for proper disposal.


Step 4: Flush the Gearbox


After draining, it's helpful to flush the gearbox with a specialized cleaning solution to remove any debris or old oil residue.


Step 5: Refill with Fresh Gear Oil


Once the gearbox is clean and dry, refill it with the manufacturer-recommended gear oil. Do not overfill; ensure the level is correct according to the specifications.


Step 6: Replace the Drain Plug


After refilling, securely replace the drain plug and any other seals to prevent leaks.


Step 7: Run the Engine


After the oil change, run the engine for a few minutes to circulate the new oil and check for any leaks.


Step 8: Regular Service Intervals


Follow the manufacturer's recommended service intervals for changing the gear oil and servicing the gearbox.




  • Always use the type of gear oil specified by the outboard motor manufacturer.
  • Perform gear oil changes in a well-ventilated area and wear gloves to protect your skin.
  • Dispose of the old gear oil properly according to local environmental regulations.


Regular maintenance of your outboard motor's gearbox will help ensure a smooth and reliable boating experience. Always consult your owner's manual for specific instructions related to your particular outboard model.