What you need before you start

Changing oil in a push mower takes about 15 to 20 minutes and requires only a few tools you likely already have. You will need a wrench or socket set (usually 8mm, 10mm, or 12mm depending on your mower model), a drain pan or container to catch old oil, fresh oil in the weight your mower manual specifies, a new oil filter if your mower has one, and rags or paper towels. Some mowers have a drain plug at the bottom of the engine; others require you to tip the mower on its side.

Before you begin, locate your mower's manual — the oil type and capacity are printed there. If you no longer have the physical manual, search online for "[your mower brand and model] manual" and download the PDF. The manual also tells you whether your mower has a drain plug or requires tipping, and which direction to tip it (tipping the wrong way can flood the carburetor with oil and cause starting problems later).

Run the mower for two or three minutes before draining the oil, or do the work shortly after mowing. Warm oil drains faster and more completely than cold oil. Let it cool just enough that you can touch the engine without burning yourself.

Key Takeaways

  • Warm oil drains faster and more completely than cold oil, so run the mower briefly or change the oil shortly after mowing.
  • Check your mower manual to find the oil weight, capacity, and whether your model has a drain plug or requires tipping on its side.
  • If your mower has no drain plug, tip it toward the side with the air filter (not the carburetor side) to avoid flooding the engine with oil.
  • Fill the new oil to the line on the dipstick, not to the top of the filler hole — overfilling causes smoking and poor performance.
  • Dispose of old oil at a recycling center, auto parts store, or municipal hazardous waste facility; never pour it down a drain or into the ground.

Locating and removing the drain plug

Most modern push mowers have a drain plug on the underside or side of the engine block. Look for a bolt or plug sticking out from the lowest point of the engine. Place your drain pan directly underneath it. Use your wrench to turn the plug counterclockwise — it will loosen and then come free by hand. Unscrew it the rest of the way and set it aside on a clean rag.

Oil will pour out quickly. Let it drain for at least five minutes, then tip the mower slightly to encourage the last bit to flow out. If no oil comes out after you remove the plug, check your manual — your mower may not have a drain plug and instead requires tipping.

Draining oil when there is no drain plug

Some smaller or older push mowers have no drain plug. In this case, you will tip the mower on its side to drain the oil from the filler hole. Your manual will specify which side to tip it toward — always tip it toward the air filter side, never toward the carburetor. Tipping the wrong way allows oil to run into the carburetor and fuel line, which causes hard starting and rough running for weeks afterward.

Place your drain pan on the ground, then carefully tip the mower until oil flows out of the filler hole. Let it drain for several minutes. Once the flow slows, you can tip it back upright. Wipe away any spilled oil with a rag before you refill.

Replacing the oil filter (if your mower has one)

Not all push mowers have an oil filter — many small engines do not. Check your manual or look around the engine block for a cylindrical canister about the size of a soda can. If you find one, use an oil filter wrench (a specialized socket that grips the canister) to turn it counterclockwise until it comes free. Hand-tighten the new filter in place, then turn it an additional three-quarter turn with the wrench. Do not over-tighten it.

If your mower has no filter, skip this step and move directly to refilling the oil.

Refilling with fresh oil

Reinstall the drain plug by hand first, then use your wrench to tighten it snugly — do not over-tighten, as this can strip the threads. If you tipped the mower on its side, make sure it is fully upright before you refill.

Unscrew the oil filler cap on top of the engine. Pour in about three-quarters of the amount listed in your manual, then stop and check the dipstick. Pull the dipstick out, wipe it clean with a rag, reinsert it fully, then pull it out again and read the level. The oil should reach the line marked "full" on the stick. Add oil in small amounts until you reach that line — do not fill it to the top of the filler hole, as overfilling causes the engine to smoke and run poorly.

Screw the filler cap back on and wipe up any spilled oil. Start the mower and let it run for 30 seconds, then shut it off and wait two minutes. Check the dipstick one more time to confirm the level has not dropped.

Disposing of old oil safely

Never pour old oil down a drain, into the ground, or into the trash. Oil contaminates soil and water and is illegal to dispose of that way in most places. Instead, take it to a recycling center, an auto parts store (many accept oil for free), or your city or county hazardous waste facility. Pour the old oil into a sealed container or the drain pan you used, and transport it in your vehicle. Most facilities accept it at no cost.

If you changed the oil filter, wrap it in a plastic bag before you transport it, as it may still contain a small amount of oil.

Troubleshooting common problems

If the mower smokes after an oil change, you likely overfilled it. Shut off the engine, let it cool, and drain a small amount of oil until the dipstick reads at the full line. If the mower is hard to start or runs rough after you changed the oil, and you tipped it on its side to drain it, you may have tipped it the wrong way and flooded the carburetor. Check your manual for the correct tipping direction and consider having a small engine repair shop clean the carburetor.

If oil leaks from the drain plug after you reinstall it, the plug may not be tight enough or the threads may be stripped. Tighten it a quarter turn at a time until the leak stops. If tightening does not work, the plug or the engine block may need replacement — take the mower to a repair shop.

Frequently Asked Questions

How often should I change the oil in my push mower?

Most manufacturers recommend changing the oil every 50 to 100 hours of use, or at least once per season. If you mow weekly during the growing season, that is roughly every 4 to 8 weeks. Check your manual for the exact interval for your model.

Can I use the same oil weight year to year?

Your manual specifies the oil weight for your climate and season. Some mowers use 10W-30 year-round, while others call for 5W-30 in winter and 10W-30 in summer. Follow your manual — using the wrong weight can affect starting and engine wear.

What if I spill oil on the engine while refilling?

Wipe it up immediately with a rag. A small amount of oil on a hot engine will burn off and create smoke, but it will not damage anything. Let the engine cool before you start it if you spilled a large amount.

Do I need to change the spark plug at the same time?

No, but it is a good time to do it. Spark plugs typically need replacement every season or every 100 hours of use. Check your manual for the correct plug type and gap setting.