Mercury 90 HP Oil & Filter Change

Tools Needed

• 1/16" and 1" socket wrenches
• 5/8" and 10mm socket wrenches
• Flathead screwdriver
• Strap wrench
• Oil filter wrench (if available)
• Half-inch inside diameter hose
• Funnel
• Crush washers
• Gear lube pump
• Oil and gear lube

Safety

• Ensure the engine is cool before starting any work.
• Be cautious when handling oil and gear lube to avoid spills.

Steps

1. Remove the propeller using a 1/16" and 1" socket wrench.
2. Remove the drain plug for the gear oil using a 10mm socket wrench.
3. Place a catch basin under the engine to collect the oil.
4. Attach a half-inch inside diameter hose to the engine oil fitting and run it into the oil pan.
5. Remove the oil filter using a strap wrench or oil filter wrench.
6. Install the new oil filter by hand, then snug it with a strap wrench.
7. Allow the engine oil to drain completely.
8. Remove the hose from the engine oil fitting and tighten it by hand.
9. Fill the engine with 5.2 liters of oil through the fill cap at the top.
10. Allow the oil to settle, then check the level and add more if necessary.
11. Remove the upper-level plug for the gear oil using a big screwdriver.
12. Attach the gear lube pump to the drain hole on the bottom of the gear case.
13. Fill the gear case with the appropriate amount of gear lube.

Tips

• Use a block of wood to prop up the propeller while removing it.
• Be patient while draining the oil, as it may take some time.
• Dip your finger in oil to lube the oil filter gasket for better contact.
• Tighten the oil filter by hand, then snug it with a strap wrench to avoid overtightening.
• Allow the oil to settle before checking the level to prevent overfilling.