How to Change the Oil in Your Lawn Mower

How to Check and Add Oil to the Engine Crankcase

1. Prepare the Lawn Mower

   Check the engine's oil level before you start the lawn mower before each use, while the engine is still cool. If you check it after use, let the engine cool down completely to avoid accidentally touching it and burning yourself. When checking the oil, make sure your machine is on level ground; you will get a false reading if the machine is not level.

2. Check the Dipstick

   Extract the dipstick, wipe it with a clean rag, insert it back in the fill opening, and check its reading. Confirm this with a second reading. When you inspect the dipstick, check the oil level and how clean or dirty the oil looks. Your inspection will yield one of three possible results:

   • If the oil level is fine and the oil appears clean and dark amber, go ahead and mow the lawn; your engine oil is fine.
   • If the oil appears clean but the reading is low, add oil before mowing.
   • If your lawn mower's oil appears dirty, it's time to change the oil. It's fine to mow the lawn first before doing this maintenance since warm oil will drain out of the lawn mower much more easily. If the motor oil level is low, add a small amount of oil to the crankcase before mowing, then change the oil after you finish.

3. Add Motor Oil

   To add oil to the crankcase with a low oil level, insert the nozzle of a funnel into the fill opening, then pour a small amount of SAE 30 motor oil (or whatever is recommended by the manufacturer) into the lawn mower's crankcase. Do not overfill the crankcase since over-filling can cause problems.

   When filling your lawn mower engine with oil, pour in just a little bit at a time, then re-check the level. You are more likely to make a mistake if you rush. Use only a type of oil suitable for your lawn mower (check the manual when in doubt).

4. Screw in the Fill Plug

   Screw the fill plug back into the crankcase. You are now ready to mow your lawn.

   Tip

   Check your mower engine before every use. Especially as lawn mower engines grow old, they may leak slightly and "burn oil" as they operate.

How to Change the Oil in a Lawn Mower, Step-By-Step

1. Prepare the Lawn Mower

   Cover your work area with newspapers or cardboard. With smaller mowers, it may be easiest to put the mower up on a workbench to change the oil, or you can work on a garage floor or driveway covered with newspaper or cardboard. With large riding mowers, you may need ramps to elevate the mower so you can get at the drain plug below the mower.

   Have an oil pan ready to catch the oil as you drain it out of the crankcase.

   Start up the mower and let it warm up for about one minute. This slightly warms up the oil and makes it drain out easily.

   Shut off the mower, then disconnect the spark plug wire from the spark plug. Use rags to wipe away the area around the fill plug and drain plug areas.

2. Drain the Oil

   For push mowers, prop up the mower so the spark plug is facing upward. This will prevent gasoline from draining out of the machine. Place the oil pan under the mower.

   Use a socket wrench in a clockwise direction to unscrew the oil drain plug. Allow the oil to drain out into an oil pan. Replace the drain plug into the drain opening, making sure it is tight.

   Transfer the old oil into a container you can seal for proper disposal. Never pour used motor oil onto the ground or down a drain. Any retailer that sells motor oil can dispose of old oil—take your container of used motor oil to a filling station or oil-change outlet.

3. Replace the Oil Filter

   In lawn mowers equipped with oil filters, you may need to change the oil less frequently, since the filter will catch large particles of dirt and debris. But the filter should be changed at least once each year, or whenever the manufacturer recommends it.

   Locate the oil filter, and remove it by twisting the cartridge counter-clockwise until it screws loose. Often you can do this by hand, but a filter wrench can make this easier.

   Carefully wipe off the metal rim where the oil filter seals against the engine. Examine the rubber seal on the new oil filter. If it is dirty at all, wipe it clean, then wipe a thin layer of oil onto the rubber seal.

   Thread the new filter onto the engine and tighten it by hand until the rubber seal gently compresses against the metal rim of the filter mount. Tighten the filter a little bit more using a filter wrench.

4. Refill the Engine Oil

   Remove the oil fill plug on the mower. (Some mowers may have two plugs; either one can be used to fill the crankcase.) Insert the tip of a funnel into the fill opening, and slowly pour fresh motor oil into the engine crankcase. Use only the amount of oil recommended by the manufacturer and avoid overfilling.

   As the level nears the full amount, use the filler plug dipstick to check the oil level. Make sure to wipe the filler stick clean before each check.

   When the crankcase is full, screw the filler plug back into the fill opening, and wipe up any oil that has spilled on the floor or lawn mower chassis. Reconnect the spark plug wire.

5. Get Ready to Mow

   Your lawn mower oil is now changed. Make sure to check the oil level and the condition of the oil before every use. Keeping your engine full of clean oil and maintained at the proper levels is perhaps the most important thing you can do to keep a lawn mower operating efficiently for many years.