How to Change Lawn Mower Oil (and What Type to Use)
In This Guide
Clean oil is the cheapest insurance there is for a small engine, yet it is the step most owners skip. Knowing how to change lawn mower oil takes about fifteen minutes, costs a few dollars, and adds years to the engine. Below we cover which oil to use and how much, the simple steps to drain and refill it, and how often the job should be done.
What Type of Oil Does a Lawn Mower Need?
Most small four stroke mower engines run on detergent oil rated SAE 30 for warm weather or 10W-30 for a wider temperature range. Synthetic 5W-30 or 10W-30 is an excellent choice and flows better in cold starts. Always check your owner manual, since the engine maker lists the exact grade.
| Oil grade | Best for |
|---|---|
| SAE 30 | Warm season mowing, most walk behind mowers |
| 10W-30 | Varying temperatures, riding mowers |
| Synthetic 5W-30 or 10W-30 | Cold starts and longer service life |
How Much Oil Does a Lawn Mower Hold?
Capacity depends on the engine, but as a guide, most walk behind mowers hold about 0.5 quart, and most riding mowers hold 1.5 to 2 quarts. Always fill to the full mark on the dipstick rather than to a fixed amount, since overfilling causes smoke and leaks.
Tools and Supplies
- Fresh oil of the correct grade
- A drain pan or container
- A socket or wrench if your mower has a drain plug
- An oil extractor or turkey baster if it drains through the fill tube
- Rags and a funnel
How to Change the Oil Step by Step
1. Warm the engine
Run the mower for a couple of minutes. Warm oil drains faster and carries away more debris.
2. Disconnect the plug wire
Pull the spark plug wire so the engine cannot start while you work.
3. Drain the old oil
Empty the fuel tank or keep it low, then either remove the drain plug into a pan, or tip the mower carefully with the filter side up to pour out through the fill tube. An extractor pulls it cleanly through the dipstick tube with no tipping.
4. Refill to the full mark
Add fresh oil slowly through the fill tube, checking the dipstick as you go. Stop at the full mark. Do not overfill.
5. Reconnect and test
Wipe up spills, reconnect the spark plug wire, start the mower, and check for leaks.
How Often Should You Change Lawn Mower Oil?
On a brand new engine, change the oil after the first 5 hours of use to clear out break in debris. After that, change it once a season or every 50 hours of running, whichever comes first. Mowers that work hard, run in dusty conditions, or cut large areas benefit from more frequent changes.
Why Fresh Oil Matters So Much
Oil lubricates, cools, and cleans the engine. As it ages it thins, fills with grit, and stops protecting the moving parts, which leads to overheating and wear. A few dollars of oil once a season prevents repairs that can cost more than the mower. It is the best value maintenance you can do, and it pairs naturally with a yearly tune-up.
Rather Have a Real Technician Handle It?
A Wildwood technician comes to your driveway, diagnoses the problem, and fixes it on the spot, usually in about an hour. More than 10,000 repairs completed since 2019, with flat rates quoted before we arrive so there are no surprises.