Can You Use Car Motor Oil In A Lawn Mower?

In case you're wondering if you can use the same engine oil that you use for your car on your lawn mower, you've come to the right page. We've asked our automotive experts if you can do so and here's what they have to say.

You cannot just use any automotive oil in your lawn mower. The oil has to have adequate Zinc content, fewer additives, and can perform well under extreme pressure before you can use it for your lawn mover. 

Read further so we can help you understand better why you can't use just any car motor oil on your lawn mower. We'll tell you about the difference between small engine oil and car oil. We'll also share with you some maintenance tips to make your lawn mower last longer and always stay in great condition.

A lawn mower cutting green grass in backyard, Can You Use Car Motor Oil In A Lawn Mower?

Is lawn mower oil different from car oil?

A lawn mower makes cutting grass in your yard so much more efficient. But of course, for it to do that, it has to have fuel and oil. And since mowers don't consume a lot of engine oil, one may be tempted to use the automotive oil that's on standby in the garage.

Stop right there before you damage your mower's engine. Lawn mower oil or small engine oil is different from car oil. They are intended for different applications and have different content that makes them effective to use in specific types of engines.

Cutting the long grass with a green lawn mower in the summer sun

Is there a difference between small engine oil and car oil? 

Yes, there is a difference between small engine oil and car oil. The first one is rather obvious because it refers to their application. The other distinction pertains to their Zinc levels. 


As the name implies, small engine oil is used in a piece of moving equipment that has a small engine. They are usually referred to as air-cooled engines because they don't come with a thermostat to help regulate the temperature in the engine.

The oil serves as a coolant to the engine. So, if you have to use your lawn mower when the weather is really hot, your oil is working extra hard to keep the temperature inside your engine cool (or else it'll overheat and get damaged). This is why lawn mowers need engine oil that can perform well in high temperatures so that they won't break down easily.

Meanwhile, cars obviously have a bigger engine compared to lawn mowers. They are equipped with a thermostat that controls the temperature level in the engine. This is why car engine oils don't need to perform as hard as small engine oils in keeping the engine cool. 

Zinc level

Small engine oils contain a higher zinc level than car oils. Zinc helps the oil perform better especially when it is used under extreme pressure. It also serves as an antioxidant so that there won't be any significant chemical changes when oil reacts with oxygen. All in all, Zinc prevents the break down of oil and helps it last longer even when used under stressful circumstances.

On the other hand, automotive oils have a very low level of Zinc content. While Zinc helps protect the camshaft, it can harm your engine's combustion system. It can damage the catalytic converter when Zinc turns to ash.

Small engines are also more sensitive and less sturdy. You should be very careful in scrutinizing the ingredients of your oil as the use of additives and alternatives can harm the engine. These are commonly found in automotive oils. This is why you should only use high-quality oil for your lawn mower. Protect its engine and you'll benefit from its performance and enjoy using it for a longer period of time.

What happens if you put car oil in a lawn mower?

Ride-on lawnmower in garden

The answer here would depend on the viscosity and grade of the oil that you're using. 

If the car oil has a higher viscosity, then it can affect how your lawn mower runs. Since the oil isn't able to flow quickly, your mower will run at a slower rate. If you use the wrong oil grade, it can decrease fuel efficiency. Your engine needs to work harder which can also lead to its failure.

Always use the oil viscosity and grade that's recommended in your owner's manual to maximize your engine's performance.

When should I change the oil in my lawn mower?

When we hear engine oil, we always think that it is essential in lubricating the moving parts of your lawn mower. But in reality, oil does a lot more than that.

The oil in your mower acts as a cooling agent, a buffer to keep the pH level inside your engine stable, and a cleaner to prevent carbon and other impurities from reaching the engine.

This will give you a better appreciation of how important engine oil is for your lawn mower. As such, you can't afford to have it go bad inside your mower. That's why you need to change the oil regularly. But you should always check your user manual for the manufacturer's specific instructions regarding the best time to change the oil in your lawn mower.

But in general, it is recommended that you change the oil at least once every mowing season or after 50 hours of running time for push mowers whichever comes first. For riding mowers, the running time can be 100 hours. 

If your mower is new, manufacturers usually advise you to change the oil immediately after your initial usage or about 5 hours of operation.  

If your mower has been in storage for a long time, it is a good practice to check the condition of the oil first before you use it again. Extreme weather conditions can affect its quality. It could also be that dirt and dust have settled in your oil making it inappropriate to use on your engine or else you'll risk getting it damaged. When this happens, you should change the oil in your mower.

What happens if you don't change the oil in a lawn mower?

Red mower in garden

Changing the oil of your mower is part of giving it proper care and maintenance. Simply put, the engine of your mower can be damaged if you don't change the oil regularly. Oh, and consider the other internal parts as well.

The oil inside your lawn mover can get dirty over time and it'll start to break down. When this happens, it loses some of its important properties such as its detergents and cooling agents. Its quality depreciates and believe us, you wouldn't want to use old oil in your engine.

How can dirty oil lubricate your mower's engine and protect the other components properly, right? In this case, it would cause more harm than good. 

There are also times when oil turns thick and black especially when your mower has to work under extreme temperatures. With a thicker consistency, the oil will not be able to flow smoothly to certain parts of your mower that need to be lubricated. 

So, make it a point to change your mower's engine oil regularly as recommended by the manufacturer in your user manual. You would only need a small amount of oil anyway.

This is a small price to pay for the protection it gives to your engine and the internal components of your lawn mower. As you do this, you are helping extend the life of your mower. 

What oil is best for a lawn mower?

In order to provide your lawn mower with the best engine oil, it is important to consider the following factors when choosing:

Range of Temperature

This is specific to the area where you live. Certain engine oils perform best under different temperatures.

For example, those who experience hotter temperatures are better off using 15W50 oil since it is expected to work well with temperatures ranging from 20 to 120 degrees Fahrenheit. Meanwhile, 5W30 oils can withstand colder temperatures from 40 to -20 degrees Fahrenheit. 

Type of Lawn mower

There are different types of lawn mowers and their engines will also differ. Ride mowers have a bigger engine and you can use the engine oil that you use on your vehicles on this type of mowers such as 10W-30 or 10W-40.

Some walk mowers only have 2-cylinder engines. They do not have a separate unit for lubrication. This means oil and fuel are mixed together. As such, they require a higher quality of oil and a specific formulation for mixing fuel and oil together.


This might also refer to the brand of engine oil that you will get. Of course, it's recommended that you buy from well-known brands since their products have been tested by thousands of other users. You should only use high-quality engine oil for your lawn mower so that it will perform better and last longer.

Take note of these factors when choosing your mower's engine oil. Don't just go with any oil that's available if you want to get top performance from your mower.  But always refer to your user manual for the manufacturer's specific recommendations. After all, they know their products best.

Final Thoughts

It's important to put good oil in your mower if you want to get the most out of your investment in this nifty equipment. Always consider the range of temperature where you're using it, the quality of the engine oil, and the appropriate oil for your mower's engine type to feed it with the best oil for its system.

For other discussions about motor oil, you may read the following posts:

10 Top Motor Oil Brands – How to Choose Yours

Does Castrol Motor Oil Contain Zinc?

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