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Can You Use Car Oil in a Lawn Mower? (What Mechanics Say)

Lawn mower engines are similar to car engines in many ways, and if you’re in a pinch, needing to change or add oil to your lawn mower, it may be tempting to use what’s nearby. When using your lawn mower, you might have wondered, is it okay to use the motor oil in your car? 

You can use some types of car oil in a lawn mower, particularly if you have one of the more recent four-stroke engine lawnmowers. A four-stroke mower engine can generally run on SAE 30 or 10W-30 oil, but if you have a two-stroke lawn mower engine, you must use unique oil.

This article will discuss what type of oil is safe to use in your lawn mower engine. It’s important to read your manufacturer’s instructions to ensure you’re using the correct type of oil for your specific engine.

Is Lawn Mower Oil Different Than Car Oil?

Many small engines, such as those used in push lawnmowers or string trimmers, require special oil made specifically for your engine. For example, the engines on ECHO brand small appliances are required to use their own oil. 

Lawn mower oil isn’t different from car oil. Small engines like lawnmowers consume the same oil as automobiles, but owners should double-check instructions since these tiny motors are susceptible to additives and alternatives.

The most important thing you can do when using car oil in your lawn mower is to ensure you have the correct type of oil. There are multiple grades of automotive motor oils that vary across manufacturers, so it’s essential to read the instructions specific to your model and brand.

Red Lawn Mower Cutting Grass
Check the manufacturer’s website if you can’t find the manual.

Two-Stroke vs. Four-Stroke Lawn Mower Engines

The type of engine your lawn mower has is an important distinction. Two-stroke engines are found in most small, inexpensive lawnmowers and use low-quality oil with anti-wear additives. 

Four-stroke engines have better lubrication during the power stroke and should only be used when clearly indicated by the manufacturer. Four-stroke engines typically use the same oil as cars.

Two-Stroke Engine Oil Types

You should only use clean, high-quality fuel to get the most out of your two-stroke engine. We don’t recommend using used or recycled motor oil in a two-stroke engine because it can cause inadequate lubrication, premature carbon buildup, and decreased performance. Two-cycle oil is made for this type of engine and typically contains additives to reduce air pollution. 

Four-Stroke Engine Oil Types

Four-stroke engines are different from two-stroke engines in that they have an intake stroke (gas moves into the cylinder), compression stroke (gas gets squeezed), combustion stroke (combustion occurs), and exhaust stroke (exhaust exits). The power strokes are when all the work is being done in the engine.

There are two primary classifications for four-stroke motor oils: conventional and synthetic. Conventional oils are typically made from crude petroleum oil, while synthetic oils often contain no petroleum at all. Within these two classes, you’ll find API-certified ratings ranging from SG to SH for SAE grades or viscosity levels.

What Happens if You Put Car Oil in a Lawn Mower?

When it comes to your lawn mower, the best oils are usually synthetic. While you can use automotive oil in your lawn mower, it must be high-quality.

If you put car oil in your lawn mower, there’s a good chance nothing significant would happen initially. However, if low-quality motor oil is left untreated or unchanged for long periods, it could become detrimental to your engine over time. 

At worst, poor oil can cause your engine to become inefficient over time, potentially harming the engine or creating a genuine safety risk. This is where the question of car oil comes in. To summarize, yes, you may use car oil to power your lawn tractor, but it must be of good quality.

As a rule of thumb, using high-quality synthetic oil is one of the best options. The oil must be rated for use in your specific engine. Additionally, many people recommend changing the oil after every 50 hours of use.

Is It Okay To Put Synthetic Oil in a Lawn Mower?

When you’re looking for oil for your lawn mower, it’s best to buy something designed specifically for the job. Furthermore, it should contain additives to help grip the grass and protect against rusting. One option may be synthetic car-engine oil, which usually possesses enough lubricating properties to keep your mower running smoothly all year round. You can use diesel, too, if that’s all you have available. 

It is okay to put synthetic oil in a lawn mower since it’s designed explicitly for engines and has additives that form a protective barrier where metal meets metal in the engine. Synthetic oil has lubricating properties to keep your mower running smoothly all year round.

It’s a good idea to use synthetic oil because it’s already of a suitable viscosity to keep the piston rings from being overworked. Plus, it may have additives to give your mower’s motor an added boost. Non-synthetic oils contain sulfur, which tends to accumulate in carburetors and exhaust manifolds. This potentially causes harm to a lawn mower by deteriorating the metal components.

Can You Use 5W30 Motor Oil in a Lawn Mower?

Canister of 5w-30 synthetic motor oil with yellow bubbles surrounding it

Synthetic oils are preferred over mineral oils because they’re more efficient and can be used in extreme weather conditions. 5W30 motor oil is a common viscosity. It’s frequently found in automobile engines and preferred for the wide temperature ranges it can be used in, making it a good choice for mowers.

You can use 5W30 motor oil in a lawn mower. The oil has a viscosity of 5, which means it’s quite thin and has a 30-weight grade rating, ideal for lawn mower engines. To keep your lawn mower engine happy and healthy using car oil, the oil must be high-quality. 

Synthetic oils are often superior to conventional motor oils since they provide better protection and lubrication during cold weather conditions. Because of its ability to flow at extremely cold temperatures down to -30 degrees Fahrenheit, 5W30 synthetic oil has little chance of congealing when the differential temperature drops below freezing. 

This makes it ideal for use in lawnmowers that may be exposed to varying climates, such as riding mowers and zero-turn sit-on-top mowers. Synthetic oil is also better because it has a uniform molecular structure. The molecules don’t clump together as easily as conventional oil, which can interfere with the engine’s operation and result in roughness and poor performance.

Can You Use 10W30 Car Oil in a Lawn Mower?

Using 10W30 motor oil in a lawn mower is very similar to using 5W30. The only difference is that it has a slightly thicker viscosity, which means the oil won’t be as easy to pump around your lawn mower engine. This causes less fuel efficiency and premature wear of the mower’s engine. 

You can use 10W30 car oil in a lawn mower if you have an older model or a model with either a carburetor or manual choke. These models are known for their difficulty starting up when exposed to cold temperatures, so they’re more likely to need thicker oils. 

However, if your lawn mower has an electronic ignition, it shouldn’t even be exposed to these sorts of conditions and is only be used in fair weather. 

What Oil Is Best for a Lawn Mower?

Middle age man adding oil to lawn mover in the garden

When choosing oil for your lawn tractor, you should look to use synthetic oil that is specifically designed to meet US standards and specifications. 

When it comes to the best oil for lawnmowers, your best option is SAE 30/SAE 10W-30 oil. These oils are great for use in warmer climates. Even if you live in a cold region, you aren’t going to start using your lawn care equipment until it’s warm again.

To choose the right motor oil for your lawn mower, consider purchasing an oil that is SAE 10W-30/SAE 30.

The best kind of motor oil for your mower is a full synthetic variety. These oils have been specifically designed for use in outdoor power equipment.

Choose a quality synthetic motor oil based on US standards and specifications. This will ensure the proper weight is used to protect your engine when starting it at lower temperatures. It will also avoid sacrificing viscosity or wear at higher temperatures when you are working hard to cut tough grasses.

You can choose any brand of full synthetic oil based on SAE 10W-30/SAE 30 criteria; all brands meet or exceed the standards outlined by American Petroleum Institute (API). 

How Often Do You Change Lawn Mower Oil?

Lawn mower oil needs to be changed when you notice the oil is dirty or foamy in color and contains metal shavings. It also needs changing if your lawn mower has been burning oil excessively.

Change your lawn mower’s oil as often as every 50 hours (about once per season) to extend its life further. Some change their mower oil more often, while some mow more lawns between changes. It’s a matter of personal preference and observations made during regular maintenance checks.

If you cut too many wet grasses, clogged grass might reduce airflow resulting in incomplete combustion, which causes low power and black smoke to come out of the exhaust system. This can cause a lack of lubrication due to high temperatures, so it’s best to change the motor oil sooner than later when this occurs.

If you’ve been running your equipment on used or dirty oil, the engine may be in need of serious repair work. You should take it to an authorized service shop for tune-ups and repairs.

Man Fixing Lawn Mower Engine
Always find an authorized mechanic.

When you’re buying oil, make sure to follow the owner’s manual for your specific mower model. There are different types of oils that have been designed to work in different temperatures, so be careful when using any type of oil not recommended by the manufacturer. 

For cold or moderate climates, select an oil that can be used down to -10°F (-23°C), whereas in hotter climates, choose an oil that is able to withstand higher temperature levels around 210°F (100°C). 

Different manufacturers have varied opinions on how often a person should change lawn mower oil. Some recommend monthly oil changes, while others recommend every few months, so your best bet is to check levels regularly and change it when necessary. You’ll need to change the oil when it appears dirty or burnt, but sometimes the issue may be something as simple as adding oil.

Changing Your Lawn Mower’s Oil

Changing the oil in your lawn mower is very easy. Before beginning work on your mower, make sure the engine has cooled down. Once it’s cool, open up your lawn mower’s hood and find where the oil tank is housed. 

To change the oil in your mower:

  1. Locate and unscrew the cap to get inside the oil tank. Some models may require you to remove screws or bolts before accessing the top of the tank. 
  2. Drain all of the old oil from the motor. 
  3. Once it seems like no more will come out, replace it with fresh oil. Wait until you see the fresh oil start flowing so you know that none of the old oil remains.
  4. Once all of the old oil has been from your machine’s engine, replace the cap.
  5. Wipe off any excess oil from outside of your mower and replace any parts you removed to access the tank. If a hose was attached to the tank, be sure to replace it as well. 
  6. Allow some time for the engine to run. This allows the fresh oil time to get into all of the right places in your machine’s motor, so you don’t have problems when you cut grass again in future weeks.


Using automotive oil in your lawn mower is one of the easiest ways to take care of your machine, but it only provides you with good results for so long. Be sure to use synthetic oil in your lawn mower when you change it.  Over time, this will help the machine last longer and operate better than using regular oil.

The best way to keep a lawn mower running smoothly is by routinely changing its oil–about once or twice during the mowing season, depending on how often you use it.

For more, check out 2 Best Lawn Mower Engine Brands (Based on Consumer Ratings).