How to Change a Mercruiser's Gear Lube

Maintaining the lower unit on a Mercruiser engine provides years of trouble-free operation. Maintenance on the lower unit begins with changing the oil every fall before putting the boat away. This ensures there will be no water to freeze and damage your Mercruiser engines lower unit.

Instructions

Difficulty: Moderately Easy

Things You’ll Need:

• Proper weight oil
• Standard screwdriver
• Oil pan

1. Place your Mercruiser outboard in a straight up-and-down position and find the upper and lower drain plugs. Set the oil drain pan beneath the plugs.
2. Use a standard screwdriver to open and remove the lower plug only. Oil will begin to drain slowly allowing you to check the position of the drain pan before continuing.
3. Remove the upper drain plug and allow the oil to drain for 10 minutes or until it is no longer dripping from the lower drain plug.
4. Refill the lower unit of the boat through the lower drain hole. You can either use a pump or squeeze bottle. Continue filling until clean oil begins to flow from the top drain hole and no longer contains air bubbles.
5. Seal the bottom drain hole with the bottle or your finger while you screw the upper drain plug into place.
6. Locate the lower drain plug and insert it as quickly as possible so as little oil as possible escapes. Check that both drain plugs are secured and tight before wiping all oil from the housing.

Tips & Warnings

• Always fill the lower unit on your Mercruiser engine to the recommended level. Failure to do so will damage the unit.
• Always dispose of used oil at a used oil recycling and collection center.