Learning how to change a lawn mower oil is a fundamental skill for any homeowner. Changing the oil yourself is a straightforward maintenance task that requires only a few basic tools. It saves you money and ensures your mower’s engine runs smoothly for seasons to come. This guide will walk you through every step, from preparation to cleanup.
How To Change A Lawn Mower Oil
This section provides the complete, step-by-step procedure. Before you start, always consult your mower’s owner’s manual for specific recommendations on oil type and capacity. The manual is your best resource for your particular model.
Tools And Materials You Will Need
Gathering everything before you start makes the job quicker and cleaner. You likely have most of these items already in your garage or shed.
- Fresh engine oil (check manual for type and quantity)
- A drain pan or old container
- A funnel
- Socket wrench or box-end wrench (size specified in manual)
- Clean rags or paper towels
- Latex or nitrile gloves (optional but recommended)
- A piece of cardboard or a tarp to work on
Step 1: Prepare Your Lawn Mower
Safety is the first priority. Begin by running the mower for 5-10 minutes to warm up the oil. Warm oil flows out more easily and carries more contaminants with it. Then, turn off the engine and disconnect the spark plug wire. This prevents any accidental starts while you’re working.
Move the mower to a flat, level surface. Tilting it can lead to an incomplete drain. Place your cardboard or tarp underneath to catch any drips and protect your driveway or garage floor.
Step 2: Locate And Clean The Drain Plug
Consult your manual to find the oil drain plug. On most walk-behind mowers, it’s on the underside of the deck, near the base of the engine. On some riding mowers, it may be on the side. Wipe the area around the plug with a rag to prevent dirt from falling into the engine when you remove it.
Step 3: Drain The Old Oil
Position your drain pan directly under the plug. Using the correct size wrench, carefully loosen and remove the drain plug. Allow the oil to drain completely into the pan. This can take several minutes. Be patient to get as much old oil out as possible.
Once drained, clean the drain plug and its threads with a rag. Inspect the washer on the plug; if it’s cracked or worn, it’s a good idea to replace it to prevent future leaks.
Alternative Method: Using A Siphon Pump
If your mower doesn’t have a drain plug, you can use a siphon pump. Insert the pump tube into the oil fill tube and pump the old oil out into your drain pan. This method is a bit messier but effective.
Step 4: Reinstall The Drain Plug
Once oil stops dripping, reinstall the drain plug. Thread it in by hand first to avoid cross-threading, then tighten it securely with the wrench. Do not overtighten, as this can strip the threads on the engine casing.
Step 5: Add The New Oil
Locate the oil fill tube, which usually has a dipstick attached. Place your funnel in the opening. Slowly pour in the fresh oil. Check your manual for the correct capacity—it’s usually between 15 to 24 ounces for walk-behind mowers. It’s better to add slightly less than the full amount initially.
After adding most of the oil, wait a minute for it to settle, then use the dipstick to check the level. Wipe the dipstick clean, reinsert it fully, then pull it out to check. Add oil in small increments until the level reaches the “Full” mark on the dipstick. Do not overfill.
Step 6: Final Checks And Cleanup
Reconnect the spark plug wire. Wipe up any spilled oil from the mower’s engine and deck. Properly dispose of the old oil at a recycling center or an auto parts store that accepts used oil. Never pour it on the ground or into a drain.
Start the mower and let it run for a minute. Check under the engine for any leaks around the drain plug. Turn it off and check the oil level one more time, topping up if necessary.
Choosing The Correct Oil For Your Mower
Using the right oil is as important as the change itself. The wrong type can reduce engine performance and lifespan.
Understanding Oil Viscosity
Viscosity refers to the oil’s thickness. For lawn mowers, you’ll typically see grades like SAE 30 or 10W-30. Your owner’s manual will specify the correct viscosity for your climate. SAE 30 is common for warmer weather, while 10W-30 is better for areas with colder springs and falls.
Synthetic Vs Conventional Oil
Conventional oil is a fine, cost-effective choice for most mowers. Synthetic oil offers better performance in extreme temperatures and can provide longer intervals between changes, though it’s more expensive. Check if your manual recommends one over the other.
When To Change Your Lawn Mower Oil
Following a regular schedule is key. A common rule is to change the oil every 25-50 hours of operation or at least once per mowing season. If you only use your mower lightly, an annual change is still a good idea. Oil breaks down over time, even when not in use.
- First Change: After the first 5 hours of use on a new mower (to remove break-in metal particles).
- Regular Changes: Every season or every 25-50 hours thereafter.
- Visual Check: If the oil on the dipstick looks very dark and gritty, it’s time for a change.
Common Mistakes To Avoid
Being aware of these pitfalls will help ensure a successful oil change.
Overfilling The Engine
Adding too much oil can cause excessive pressure and lead to leaks or engine damage. Always add gradually and use the dipstick to check the level accuratly.
Using The Wrong Oil Type
Do not use automotive oil in your lawn mower unless the manual explicitly states it’s acceptable. Small engines have different requirements.
Not Disposing Of Oil Properly
Used motor oil is a major pollutant. Always take it to a certified collection site. Most auto parts stores and service stations will take it for free.
Frequently Asked Questions
How Often Should I Change My Lawn Mower Oil?
You should change your lawn mower oil at least once per mowing season. For heavy use, change it every 25-50 hours of operation. Always do the first change after the initial 5 hours on a new mower.
Can I Use Car Oil In My Lawn Mower?
It is not recommended. Most car oils contain additives that can harm small engines. Always use a detergent oil classified for service SF, SG, SH, SJ, or higher, as specified for small engines.
What Is The Best Way To Drain Lawn Mower Oil?
The best way is to use the engine’s drain plug if it has one. If not, a fluid siphon pump inserted into the oil fill tube is the next best method for removing the old oil.
Do You Change Lawn Mower Oil Hot Or Cold?
Change the oil when it is warm, not hot. Run the engine for a few minutes to warm the oil, then turn it off and let it cool for a minute or two. This makes the oil flow better without risking burns from hot components.
What Happens If You Don’t Change Your Lawn Mower Oil?
Old oil loses its lubricating properties and becomes contaminated with dirt and metal particles. This leads to increased engine wear, overheating, reduced performance, and can ultimately cause engine failure, which is costly to repair or replace.