Get Your Doubts Cleared: What Kind of Oil Should I Use in My Lawn Mower?

Oil plays an important role in how a lawn mower’s engine operates.

Without oil, the engine is increasingly likely to overheat. 

In fact, the heat produced by friction between the piston and the cylinder walls can be so intense that it causes the engine to “Seize Up.” In some of these cases, the damage can be so bad that it completely kills the lawnmower engine.

With so many type of lawn mower oils out there, it can be hard to know what kind of oil does a lawn mower take.

Using correct type of oil for lawn mower doesn’t have to keep you guessing! In this post you’ll learn what kind of oil you should use for lawn mower and if you can use car oil in a lawn mower?

Let’s dive in!

What Kind Of Oil Should I Put In My Lawnmower?

What Kind Of Oil Should I Use In My Lawn Mower

so, what kind of oil for lawn mower? To truly answer this question, you have to take into account the type of engine your lawnmower has.

While there are some tweaks in design from one manufacturer to the next most lawn mower engines are either “Two Stroke” or “Four Stroke.” You might also see this expressed as “Two-Cycle” or “Four Cycle.”

These terms essentially identify how many motions or “Cycles” the piston has to go through to deliver its rated amount of power.

The type of oil each engine uses is different. Using the wrong one can potentially damage the lawnmower engine, gum up the carburetor, cause it to smoke excessively, or affect the spark plug.

Most four-stroke or four-cycle lawnmowers will use SAE 10W-30. Some new mowers come with a quart of oil that you can use to top it up or to change the oil.

It’s always a good idea to check the owner’s manual. There are some lawn mower manufacturers who now recommend Synthetic SAE 5W-30.

With a two-stroke or two-cycle lawnmower engine, you need to mix a special oil directly with the gasoline.

It’s best to do this in a separate gas can rather than trying to simply pour some into the lawn mower’s gas tank.

can you use car oil in a lawn mower?

Oil is formulated in different ways depending on their intended use. This is largely based on the temperatures created by the moving parts of the engine.

Using the car oil in a lawn mower can cause a variety of problems. This includes things like smoking, trouble starting, and even potentially seizing the piston in the cylinder.

Here is a list of some of the more common oils, and where they are typically used.

  • SAE 30 is a somewhat common oil for small four-stroke engines. 
  • SAE 10W-30 is most commonly used in cars and truck engines. Its temperature raise can vary and tends to be the preferred oil for four-cycle engines that need to run in cold conditions. 
  • Synthetic SAE 5W-30 is very similar to 10W 30. It’s also more common for older, high mileage engines that may have suffered a little wear and tear. 
  • SAE 5W-30 has a reputation for being able to handle very cold temperatures. Some newer four-cycle snow blowers and ice augers will use this type of oil to make sure they start in the depths of winter.
  • 15W-50 can handle a wide range of temperatures and can stand up to frequent, continuous use. It’s relatively common for things like pressure washers and commercial use lawn tractors. 

Synthetic oils tend to work at all temperatures. There are some people who advocate using synthetic oil with an older engine.

Just keep in mind that you will still need to change the oil with the same frequency you normally would.

Mixing Gas & Oil for Two-Cycle Lawn mower?

Right off the bat, it’s important to bear in mind that there are different types of two-cycle oil. Using the wrong one can potentially cause problems in a two-stroke engine.

With most two-stroke lawn mowers you will need to use two-cycle oil “For Air-Cooled Engines.” Still, it’s always a good idea to double-check the owner’s manual.

It’s also worth noting that different two-cycle engines are designed to run on different oil to gasoline mix ratios.

Most manufacturers will print the preferred ratio on the lawnmower engine hood, or they will stamp it into the metal near the fuel tank. It will also be printed in the owner’s manual if you still have it.

If you have a steady hand, a sharp eye, and you have a little experience mixing oil and gasoline to the right ratio, you can potentially save a little money by buying the big jug of two-cycle oil.

I have done this and I get it right more times than I’ve gotten it wrong. When you do get it wrong though, it can cause a lot of problems.

What is the best 2 cycle engine oil to gas ratio?

If this is your first time mixing two-cycle oil in the correct ratio, I would recommend looking for one of the premeasured bottles.

Many manufacturers make them at the exact volume needed to mix it to the correct ratio, with a single gallon of gas.

Yes, it does cost a little bit more, but it spares you fiddly measuring and delays.

All you have to do is pour it into a dedicated gas can. Then add exactly one gallon of fresh gasoline at the pump.

It’s also a good idea to clearly mark the gas can with a black permanent marker.

Note that it’s for two-cycle oil and gas so that you don’t accidentally use it for something else.

While you are at it, I’d recommend writing the mix ratio, and maybe even the lawnmower it’s meant to be used for.

Do I Need To Change The Oil In A Four Stroke Engine?

Older four-stroke lawnmower engines need to have the oil changed seasonally.

Maybe more if you have a large yard and you are working your riding mower hard on a weekly basis.

Double-check your owner’s manual to see what the manufacturer recommends.

What Is A Check And Fill Oil System?

Some newer mowers are designed to have a “Check and Fill” but not change the oil system. While this might feel counterintuitive, it is a feature engineered into newer small motors.

All you have to do is check the oil reservoir’s dipstick every two or three mowing sessions. If it’s low, just top it up.

With this type of oil management system, changing the oil is very hard, as most don’t have a traditional oil drain.

If there is a problem with the oil, from something like rainwater managing to invade the reservoir, you will need to use a small siphon to extract all the oil and unwanted fluids.

Then you can refill it with the correct type of four-stroke oil the manufacturer recommends.

How To Change Lawn Mower Oil?

There can be some variations from one lawnmower to the next. Most push mowers that are designed to have the oil changed will have a drain plug at the bottom of the reservoir. To change the oil you will need a few things:

  • An oil drain pan
  • Replacement motor oil
  • Replacement oil filter
  • Shop rags or clean paper towels
  • A small funnel
  • Pliers or socket for the plug
  • Oil filter wrench or pipe wrench

It can also help to have a piece of spare cardboard to put down first, just in case you spill some oil during the process.

Step 1: Start the lawnmower and let it run for a minute.

This will warm up the oil and get it flowing smoothly. Just don’t go too much past a minute or you will be dealing with hot oil and hot engine parts.

Step 2: Disconnect the sparkplug wire.

This will ensure that your lawnmower engine doesn’t accidentally start during the process.

Step 3: Remove Dart

Wipe away any old dirt and oil from the oil reservoir and dipstick. Then remove the dipstick.

Step 4: Drain the oil

For a push mower, you might need to prop the deck up to ensure that the sparkplug is facing up.

Then place a drip pan underneath and release the oil plug. With some lawnmowers, this can be done with the grip of some strong finger. However, most require a socket wrench or pliers.

Step 5: Replace the oil filter

You might be tempted to skip this step, and you might even get away with it once.

Yet as time goes on the excess particles in your oil could start to affect the performance of your lawnmower, which could lead to even more costly repair problems.

Chances are you won’t be able to do this with your bare hands. A pipe wrench or a specific filter wrench should be able to work it loose.

When you are ready to put the filter back on, put a tiny drop of new oil on the tip of your finger and lightly grease the gasket of the oil filter.

Then thread it back onto the mower by hand and tighten it with your filter wrench.

Step 6: Refill The Engine Oil

Close the plug at the bottom of the oil reservoir. Use the funnel to slowly pour new oil into the mower. Let it rest for a moment to settle out.

Then double-check it with the dipstick to make sure you are at the proper level. Try not to overfill it, as this could later damage the mower’s engine.

Step 7: Clean Any Oil Spots

Any oil drops on the lawnmower, especially on the engine, need to be wiped up with a clean shop rag.

Exterior oil deposits can smoke when they get hot, or trap dust and pollen creating a hard to clean gunk.

This Is Also A Good Time For Other Maintenance Items

Inspect The Blade

Most people change their lawn mower’s oil in the spring. It’s usually a good first step toward making sure your lawnmower will run right all summer long.

While you are at, this is also a good time to take care of other basic lawn mower maintenance issues.

Sure, it can eat up the better part of a sunny Saturday afternoon, but it’s better to do it now, than under the blazing heat of summer, when something goes wrong.

Usual spring maintenance items also include:

  • Topping up the tank with fresh gasoline
  • Adding Iso-Heat to deal with any potential water separation
  • Lubricating moving parts, and greasing zerk fittings
  • Cleaning or replacing the air filter
  • Checking and filling the air in the tires
  • Sharpening or replacing the lawnmower blades
  • Checking or replacing the spark plug
  • Topping up coolant in a lawn tractor
  • Checking and cleaning the carburetor

How Often Should I Change My Lawnmower’s Oil?

If you have a small lawn that needs to be cut every 7 to 10 days during the spring and summer, then chances are you can get away with changing your lawn mower’s oil every spring. This is usually enough to you by.

If you have a larger lawn, you frequently need to cut it, or you live somewhere with a long growing season you will need to change your oil every 20 to 50 hours of run time.

Most manufacturers will provide you with a specific recommendation in the owner’s manual.

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