Regularly changing your lawn mower’s oil is the single most important task for ensuring its longevity. Learning how to change lawn mower oil is a simple process that any homeowner can master in under thirty minutes.
This routine maintenance prevents engine wear, improves performance, and saves you money on costly repairs. By following a clear set of steps, you can keep your mower running smoothly for many seasons.
How To Change Lawn Mower Oil
This guide provides a complete, step-by-step walkthrough. We will cover everything from the tools you need to the final check after the job is done.
Why Changing Your Mower Oil Matters
Engine oil lubricates moving parts, reduces friction, and helps cool the engine. Over time, it breaks down and becomes contaminated with dirt, grass clippings, and metal particles.
Old, dirty oil loses its ability to protect the engine. This leads to increased wear, overheating, and can even cause the engine to seize completely. An annual oil change is a small investment for a long engine life.
Gather Your Tools And Supplies
Before you start, collect all necessary items. Having everything on hand makes the job faster and cleaner.
- Fresh engine oil (check your owner’s manual for type and quantity)
- A new oil filter (if your mower has one)
- An oil drain pan or old container
- A funnel
- Socket wrench or adjustable wrench
- Rags or paper towels
- Gloves (optional but recommended)
- A piece of cardboard or a tarp to work on
Choosing the Correct Oil
Using the right oil is critical. Most small engines use SAE 30 weight oil for standard temperatures. Some require 10W-30 for variable climates.
Always consult your mower’s manual for the manufacturer’s specific recommendation. Using the wrong oil can affect performance and void warranties.
Preparing Your Lawn Mower
Safety is the first priority. Proper preparation prevents accidents and makes the oil drain more effectively.
Step 1: Run the Engine to Warm the Oil
Start your mower and let it run for 5-10 minutes. Warm oil flows out more easily, carrying more sludge with it. Be sure to do this in a well-ventilated area.
Step 2: Disconnect the Spark Plug
Turn off the mower. Locate the spark plug wire and disconnect it. This is a crucial safety step that prevents the engine from accidentally starting while you are working.
Step 3: Position the Mower for Draining
Move your mower to a flat, level surface. Place your cardboard or tarp underneath. Tilt the mower carefully, usually with the air filter side up, to avoid fuel or oil leaks into the carburetor. Check your manual for the best draining position.
Draining The Old Oil
Now you are ready to remove the old, dirty oil. There are two common methods, depending on your mower’s design.
Method 1: Drain Plug
Many mowers have a drain plug on the bottom or side of the engine.
- Place your drain pan directly under the plug.
- Use your wrench to loosen and remove the drain plug.
- Allow the oil to drain completely into the pan.
- Clean the drain plug and its threads with a rag before reinstalling it snugly.
Method 2: Siphon or Tilt Method
For mowers without a drain plug, you’ll often siphon the oil out through the fill tube or carefully tilt the mower to pour it out.
- Insert a siphon pump tube into the oil fill hole.
- Pump the oil out into your drain pan.
- Alternatively, with the spark plug disconnected, you can carefully tilt the mower over your pan to pour the oil out the fill hole. Go slowly to avoid a mess.
Ensure you let the oil drain until only a slow drip remains. This might take several minutes.
Replacing The Oil Filter
If your lawn mower has an oil filter, it should be replaced with every oil change. Not all push mowers have them, but many riding mowers do.
- Locate the oil filter on the side of the engine.
- Place your drain pan underneath it, as some extra oil will spill out.
- Use an oil filter wrench to turn the old filter counterclockwise to remove it.
- Before installing the new filter, dab a bit of fresh oil on the rubber gasket.
- Screw the new filter on by hand until the gasket makes contact, then tighten it an additional three-quarter turn as per typical instructions.
Adding The New Oil
With the old oil drained and the new filter installed, you can add fresh oil.
- Place your funnel securely in the oil fill hole.
- Slowly pour in the recommended type and amount of oil. Do not overfill. Check the dipstick frequently as you approach the full mark.
- Once filled, replace the oil fill cap tightly.
Checking the Oil Level
After adding oil, wait a minute for it to settle into the crankcase. Then, remove the dipstick, wipe it clean, reinsert it fully, and pull it out again to check the level. The oil should be between the “Full” and “Add” marks on the dipstick.
Final Steps And Cleanup
You’re almost finished. A few final checks will ensure everything is in working order.
Step 1: Reconnect the Spark Plug
Reattach the spark plug wire to the plug. Make sure the connection is firm and secure.
Step 2: Start the Engine and Check for Leaks
Start your mower and let it run for a minute. Look underneath and around the drain plug and filter for any signs of leaking oil. If you see a leak, turn off the engine and tighten the connection.
Step 3: Dispose of Old Oil Properly
Never pour used oil on the ground or into the trash. It is harmful to the environment. Pour the used oil from your drain pan into a sealed container, like the bottle from the new oil. Take it to an auto parts store, service station, or recycling center that accepts used motor oil. Most accept it for free.
Frequently Asked Questions
How Often Should I Change My Lawn Mower Oil?
For most walk-behind mowers, change the oil once per mowing season or every 25-50 hours of operation. For riding mowers, consult your manual, but it’s often every 50-100 hours. Always change it at least once a year, even if you haven’t hit the hour mark.
Can I Use Car Oil in My Lawn Mower?
Maybe, but it’s not recommended. Many car oils contain additives that can harm small engines. Always use oil that meets the small engine manufacturer specifications, which is often marked as “SAE 30 Small Engine Oil” or similar.
What Happens If I Overfill the Oil?
Too much oil can cause excessive pressure, leading to leaks, hard starting, and even engine damage. If you overfill, you can use a siphon pump or turkey baster to remove the excess until the level is correct on the dipstick.
Do I Need to Change the Oil If I Just Bought a New Mower?
Yes, you should. New engines have a break-in period where metal wear particles can contaminate the initial oil. It’s a good practice to change the oil after the first 5-10 hours of use on a new mower.
Maintaining Your Mower After An Oil Change
An oil change is part of a larger maintenance routine. To keep your mower in top shape, remember to also:
- Sharpen or replace the blade each season.
- Clean the underside of the deck to prevent rust and grass buildup.
- Replace the air filter annually.
- Use fresh fuel and consider a fuel stabilizer if storing for the off-season.
Following these steps ensures your mower remains reliable. Regular maintenance like changing the oil is the best way to avoid unexpected breakdowns and expensive repairs. With this knowledge, you can confidently perform this essential task yourself.