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What Motor Oil to Use in Your Lawn Mower

A lawn mower in the middle of a beautiful green lawn.

What motor oil to use in your lawn mower is a question that many people ask when the snow melts and the grass begins to grow. Oil is an important part of maintenance for anything with an engine, whether it’s a car, a lawn mower or a trimmer, so here are some tips on how often to change your mower’s oil and what kind to use when you do.

How Often Should You Change Lawn Mower Oil?lawn mower

With a car, oil service intervals are typically determined by how many miles you put on the vehicle, but with a lawn mower and other small engines, you measure service intervals by hours of operation.

Although you should refer to your owner’s manual if possible, you’ll typically need to change the oil in your mower every 20 to 50 hours, depending on your make and model. If you have a small yard and mow weekly, you might only need to change the oil once a year. If your yard is larger or you mow multiple times per week, you might need to change it twice a year.

Even if you don’t think you need to change the oil, there are signs that can indicate you should, regardless of how often the mower is used. If your mower is running rough or smoking occasionally, or if a visual inspection of the oil shows that it’s dark brown or black instead of the usual golden amber, then it’s time to change it.

What Motor Oil to Use in Your Lawn Mower

As with cars, the amount and type of oil you put in your mower varies depending on your model, where you live and how you use it. If you’re wondering which oil to use in your mower and have a bottle of what you use in your car, it may be okay to use it, but there are a few things to check.

First, see what the manufacturer of the mower says and follow their recommendations. As a rule, SAE-30 oil will work well in most small engines. A synthetic SAE 5W-30 provides protection to your engine over a wider range of temperatures with less consumption. There’s also SAE 15W-50, which is better for continuous use in commercial mowers or in extremely high temperatures.

Note that very old lawn mowers, trimmers and other gas-powered yard tools may be powered by two-stroke engines that operate differently from more sophisticated four-strokes. For these tools, you may need to mix your gasoline and oil together using a certain ratio, creating a special two-stroke formula. If you are not sure which type of engine you have, be sure to consult the manual.

Changing the oil in your lawn mower should be a part of regular lawn mower maintenance. Be sure to keep the oil clean and topped off so you can avoid other lawn mower issues in the future.

Check out all the lawn mower care products available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information about caring for your lawn mower, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy Flickr.


Nicole Wakelin View All

Nicole Wakelin covers the automotive industry as a freelance journalist for a variety of outlets. Her work includes news pieces, podcasts, radio, written reviews, and video reviews. She can be found in The Boston Globe, CarGurus, BestRide, US News and World Report, and AAA along with lifestyle blogs like Be Car Chic, The Other PTA, and She Buys Cars. She is active on social media with a large following on both Twitter and Instagram and currently serves as Vice President of the New England Motor Press Association.

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