What Type of Oil Should I Use in My Lawn Mower?
Your lawn mower needs the right kind of engine oil used in the right way. Read on to learn about different lawn mowers and the oil they need.
Why Lawn Mower Oil Matters
Like all internal combustion engines, lawn mower engines need oil to run. Even simple engines have many moving parts, often designed to work at extremely high speeds and temperatures. This is why the lubricating and cooling action of oil is essential. Without it, your lawn mower’s engine would quickly overheat, seize and be ruined.
Lawn Mower Oil Types
Motor oil comes in different grades, based on viscosity and how the oil behaves at different temperatures. Most mowers have what are called four-stroke engines. This means they burn straight gasoline as it comes from the service station pump, but they also require motor oil to be added separately to the crankcase of the engine. 10W30 is a common motor oil grade suitable for many lawn mowers. Your owner’s manual will tell you the exact grade required, but in almost all cases 10W30 is the right stuff for a four-stroke engines.
Any brand of oil that’s suitable for cars or trucks will work fine in your mower. All reputable oil includes a service rating in addition to a viscosity rating. Look for oil that’s designated SF, SG, SH, SJ or higher.
Some lawn mowers have two-stroke engines, and these require oil in a different way than four-stroke engines. All two-stroke engines burn gasoline and oil at the same time. In the case of lawn mowers, two-stroke oil is mixed with the gasoline before it goes into the tank. Mixing ratios of gas to oil vary, but usually range from 30:1 (4-1/4-oz. of oil to one gal. of gas) to 50:1 (2-1/2-oz. of oil to one gal. of gas). The owner’s manual for your lawn mower lists the mixing ratio of gas to oil.
Two-strokes are becoming less common because of emissions regulations, but they’re still around. How do you know if you’ve got a two-stroke or four-stroke engine in your lawn mower? Your owner’s manual is the best source of guidance.
How to Choose the Right Lawn Mower Oil
Some experts say that more expensive “small engine oil” is the only type you should put in your mower with a four-stroke engine, but that’s not true. Standard engine oil made for cars and trucks is the highest quality available today and it works optimally with all four-stroke engines. Got a two-stroke engine? Any two-stroke motor oil made for air-cooled engines, such those in chainsaws, water pumps and weed eaters, will work perfectly in your two-stroke lawn mower engine.
The best way to mix gas and oil for a two-stroke engine is to put the required amount of oil into your empty gas can, then go to the gas station and fill it up. Before using the mixed gas, give the can a shake to so the oil and gas are properly mixed.
Should I Use Synthetic Oil in My Lawn Mower?
Synthetic oil is superior to lubricants made from crude oil, and your lawn mower engine may last longer if you use synthetic. According to Briggs and Stratton, one of the world’s largest manufacturers of small engines, the use of synthetic oil does not alter required oil change intervals. Regular, non-synthetic oil works well, too. I’ve used non-synthetic in some of my small engines for 30 years, and these motors still start and run as if they were new.
When to Add or Change Lawn Mower Oil
Only lawn mowers with four-stroke engines have oil that can be checked and changed. You should check the level and top it off if necessary before each mowing session.
If your four-stroke engine lawn mower is new, change the oil after the first three to five hours of use. As parts of a new engine wear initially, the internal movement of parts releases tiny metal filings into the oil that will cause excess wear if left there. Change the oil in a broken-in lawn mower at least once a season, or no more than every 50 hours of operation. The owner’s manual for your lawn mower lists the amount of oil required, but you’ll do fine following the dip stick or oil level mark that’s part of every four-stroke lawn mower engine.