Thinking about purchasing a new car? Use our new Car Loan Calculator to estimate your monthly car payment!

How to Change the Oil in Boats

by Contributing Writer; Updated June 12, 2017

Boat other such as those used with Boat other are lubricated by an oil and gas mixture, or by adding oil separately to the engine. Older Boat other that use an oil-and-gas mixture are called two-stroke Boat other while newer Boat other that require oil added separately are called four-stroke engines. A four-stroke engine is the only type of Boat other that requires oil changes.

Under The Hood:

 How to Change the Oil in a MerCruiser 3.0

Warm up the oil in your MerCruiser by running the engine for ten to fifteen minutes. Ensure that nobody is around the engine, and that your boat (if the engine is still attached) or the engine (if detached) is properly supported. Warming up the oil will help the old oil to flow from the crankcase when you're pumping it by hand.

Screw the end of the hand pump's hose to the threaded nozzle at the end of the dipstick tube. You must remove the dipstick first.

Open the oil fill cap.

Pump the oil from your MerCruiser's crankcase by hand.

Crack the oil filter off its threads with a strap wrench before removing the filter by hand. Prepare for some excess oil to run out of the filter and onto the engine block. Clean any oil that spills from the filter with a clean cloth.

Wipe some clean engine oil around the rim of your replacement filter. This will not only help you remove the filter during your next oil change, but it will actually create a tighter seal between the oil filter and the connection point on the engine.

Attach the new filter by hand. Once the seal of the filter meets the seal of the engine, turn the filter only one half to three-quarters of a turn more.

Fill your MerCruiser with four to five quarts of 15w-30 motor oil, depending on how much it takes to fill the engine's crankcase and oil filter. Check your dipstick after filling the engine with 3.5 quarts to check your progress.

Items you will need

  • Strap wrench

  • Oil hand pump

  • Replacement filter

 How to Change the Oil on a Sugar Sand Jet Boat

Remove your boat from the water, parking its trailer on level ground. Lift your engine cover at the top of the stern under the optional swim platform.

Take out your engine oil dipstick. Push the intake tube of your oil pump down into the oil well until it hits the bottom and won't feed any more.

Place the outtake tube of the pump into a drip pan and turn your pump on according to your manufacturer's instructions. Turn off the pump when you can see that it's no longer discharging any oil into the drip pan.

Remove the pump intake tube and replace the dipstick.

Place a large rag on the engine bay floor, under the oil filter, then use an oil filter wrench to remove the filter. Rub some engine oil on the new filter's top gasket, then screw it in, tightening it at the end with a filter wrench. Use the filter and amount of oil recommended by the manufacturer for your engine size.

Remove the engine oil cap and add the amount of oil appropriate to your engine specifications. Replace the oil cap.

Items you will need

  • Oil filter wrench

  • Oil pump

  • Large rag

  • Drain pan

  • Oil filter/oil

 How to Change the Oil on an Outboard Motor

Pull the boat out of the water and put it on a trailer in order to access the outboard engine. Move the boat to a location where work can be done on the engine.

Remove the engine cover, which is secured by one or two latches. Pull down on the latch and remove the cover by lifting it straight up.

Examine the oil dipstick in the crankcase. Pull out the dipstick and wipe off the oil. Reinsert the dipstick and pull it back out to to examine the oil. If the oil has a dark color, it needs to be changed.

Trim the motor all of the way up so that the oil can easily drain out from the crankcase. Push the trim button on the throttle or instrument panel to trim the motor.

Drain the oil form the crankcase. Place an oil pan or some other container under the motor to collect the oil. Remove the drain plug from the bottom of the oil tank to allow the old oil to flow out.

Wipe off any access oil and replace the drain plug. Make sure that the drain plug has been tightened securely.

Add new oil to the engine. Remove the cap to the oil tank and place a small funnel in the opening. Slowly pour the oil down the funnel. Pull out the dipstick to check the level of the oil. Add oil until it reaches the "Full" level on the dipstick.

Items you will need

  • Socket wrench

  • Oil pan

  • Rags

  • Funnel

 How to Change the Oil in a MasterCraft X-2

Park the boat trailer on a flat, level surface, and block the wheels so that the trailer will not roll.

Open the engine cover and remove the brass bilge drain plug. Thread the oil drain hose through the bilge drain opening and slide a drain pan under the end of the hose. Open the oil cap on the valve cover and loosen the end cap of the hose with a wrench. Allow the oil to drain completely, then replace the end cap securely.

Thread the drain hose back up through the bilge drain hole. Use nylon cable ties to strap the hose to the water line on the port side of the boat to prevent it from swinging around or melting on hot metal.

Loosen and remove the oil filter, taking care not to spill any oil. Fill a new filter halfway with fresh oil and lubricate the rubber seal. Tighten it one quarter to one half of a turn past hand-tight.

Fill the engine with 15W-40 engine oil, and check the level with the dipstick. Fill it to the full line. Wipe up any excess oil that may have spilled. Run the engine for 5 minutes the next time it is in the water and check the oil level again, topping off as necessary. Check for any leaks near the oil filter and tighten the filter if oil drips from the seal.

Items you will need

  • Oil filter

  • Drain pan

  • Clean rag

  • 15W-40 engine oil

  • Wrench set

  • Wheel blocks

  • Nylon cable ties

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

More Articles