How to change your transmission oil in an Inboard engine

Changing the transmission oil in an inboard engine is essential for maintaining smooth operation and preventing costly repairs. Follow this step-by-step guide to ensure proper maintenance.

Tools & Materials Needed:

• Replacement transmission oil (check your manual for the correct type)
• Oil extraction pump (manual or electric)
• Funnel
• Container for old oil
• Clean rags
• Wrench (if needed for the drain plug)
• New transmission oil filter (if applicable)

Step-by-Step Process:

1. Warm Up the Engine

Start the engine and let it run for a few minutes to warm the transmission oil, making it easier to extract. (Not needed if you don’t want)

2. Locate the Transmission Oil Fill and Drain Points

Refer to your engine manual to find the transmission oil dipstick, fill port, and drain plug (if applicable). Some transmissions require oil to be extracted through the dipstick tube with the oil extraction pump.

3. Extract the Old Oil

• If your transmission has a drain plug, place a container under it, remove the plug, and allow the oil to drain out.
• If there’s no drain plug, use an oil extraction pump to remove the old oil through the dipstick tube.

4. Check for Contaminants

Inspect the drained oil for signs of contamination (metal shavings, water, burnt smell). If you notice issues, further inspection of the transmission system may be necessary.

5. Replace the Transmission Oil Filter (If Required)

Some transmissions have a filter that should be replaced during an oil change. Check your manual for details.

6. Refill with New Transmission Oil

• Use a funnel to pour the recommended type and amount of transmission oil into the fill port.
• Do not overfill—use the dipstick to check the level as you go.
• Get your oil here

7. Run the Engine & Check Levels

Start the engine and let it idle in neutral for a few minutes. Then, check the oil level again and top off if necessary.

8. Inspect for Leaks

Look around the drain plug and fill cap to ensure there are no leaks.

9. Dispose of Old Oil Properly

Take the used oil to a proper recycling center to dispose of it responsibly.

Popular Inboard Marine Gearboxes

Here are some of the most commonly used inboard marine gearboxes:

• Hurth (ZF)
• Volvo Penta IPS
• Twin Disc
• PRM
• Technodrive (TMC)
• Borg Warner Velvet Drive
• Yanmar
• Masson Marine

Final Tips:

• Always check your engine’s manual for specific instructions and the recommended oil type.
• Regularly inspect your transmission oil for discoloration or debris.
• If you notice slipping gears, rough shifting, or unusual noises, consider further inspection of your transmission system.

By following these steps, you can ensure your inboard engine transmission runs efficiently and lasts for years to come.

Always check your manual for the right oil type and amount!

Here is a list with what oil goes in wich gearbox: