A proper fuel mixture, as we all know, is vital for the smooth operation of any lawn mower.
With that being said, fuel mixture usually refers to a combination of fuel and oil. Some lawn mowers can have separate tanks for oil and fuel, while others may need their fuel to be premixed with oil, but still, you can’t go without oil. Or can you?
Can a lawn mower run without oil? Oil provides lubrication to the internal components of the lawn mower’s engine. A lawn mower can run without oil, but this will damage the metal parts of the engine beyond repair. Some lawn mowers have a low oil level indicator, which will prevent the mower from starting.
It certainly feels like oil is a very underrated component.
If you want to learn more about what happens when you run your lawn mower without oil and what you need to take care of, make sure to check out the rest of the article.
Why Do Lawn Mowers Run With Oil?
Regardless of what engine you are dealing with, whether it is a two-stroke or a four-stroke – a lawn mower, a leaf blower, or a car’s engine – by now you probably know that oil is a must-have ingredient.
But why exactly is it so important?
Oil has two main purposes:
- It provides lubrication to the internal metal parts of the engine. This ensures smooth movement of the piston, crankshaft, and the metal bearings.
- As a direct result of the less friction, this ensures the temperature of the internal parts of the engine stays in normal ranges, protecting the it from overheating.
Fuel on its own cannot provide lubrication; after all, it is used for a different purpose.
So people have found that adding just the right amount of oil to the fuel as it burns can not only increase the engine’s life cycle but also make it run smoothly.
How to Find out If Your Lawn Mower Needs Oil?
It is very easy to find out if your lawn mower is running low on oil.
- If your lawn mower is a four-stroke, it probably has a separate oil tank. Just take out the oil dipstick and inspect the oil level. If it is too low, add more and make sure not to overfill the oil tank.
- For two-stroke lawn mowers, you will need to add oil to the fuel itself. Make sure to follow the instructions in your user manual. Don’t run your lawn mower with clean fuel.
Make sure to check the oil level of your mower each time before using it.
While checking the oil level, make sure that the mower is in a horizontal position.
Also, keep in mind that new lawn mowers do not come with oil added. So you need to add the necessary oil or fuel mixture to your lawn mower before first use.
How Often to Change the Oil of a Lawn Mower?
Most lawn mowers will require an oil change every 20 to 50 operation hours.
However, how often and when you should add oil to your lawn mower will vary depending on the particular model you have.
Make sure to do the necessary maintenance, checks, and oil change at the right time, which can be found in the user’s manual that came with your lawn mower.
What Happens If a Lawn Mower Runs Without Oil?
Now that you know why your lawn mower needs oil, we can better understand the risks associated with running it with low, or no oil.
If an engine runs without oil for too long, it will seize. It doesn’t matter what kind of internal combustion engine it is, give it enough time, and it will fail.
The engine will seize up as a result of a combination of two things (1) the metal parts rub against each other, and (2) this produces more temperature than normal.
As the metal parts rub against each other, this damages them to the point where fine little metal pieces get chipped away. This, in combination with the excessive heat, can make parts of the crankshaft and the piston weld to the other metal parts.
On another note, the lack of lubrication can cause the piston rings to wear out prematurely as well. This can result in low compression levels.
Can a Lawn Mower Start Without Oil?
Even if there is no oil in your lawn mower, it will start and run.
Some of the newer models may be equipped with a low oil safety switch, which will prevent the mower from starting if it has little or no oil in the oil tank.
Two-stroke mowers on the other hand, will usually have no way of telling if they have enough oil or not. So they are more prone to damages in connection to low oil levels. This is why care is advised when preparing the fuel mixture.
How Long Can a Lawn Mower Run Without Oil?
Despite being not recommended, it can happen to anybody. How long your lawn mower will run without oil will vary from unit to unit. But this doesn’t mean you have a lot of leeway, so to speak.
Usually, without proper lubrication, the damage will be quick to set in. Running your lawn mower even for 1 to 2 minutes will be more than enough to create permanent damage to the internal metal parts of the engine.
The lawn mower will not explode, but there is a high risk of the engine seizing up beyond repair.
Your mileage will vary, and if you are lucky, the engine may still be repairable. However, even then there will be a lot of visible damage to the piston, crankshaft, cylinder bore, the bearings, and more.
In either case, running your lawn mower without oil even for a few minutes should be avoided at all cost.
What to Do If You Accidentally Started Your Lawn Mower Without Oil?
If you started your mower without oil, first and foremost make sure to stop it as soon as possible.
If the piston and the rest of the metal parts are completely welded together, there is nothing you can do. But if the piston moves slowly, there may be a good chance of bringing your lawn mower back to life.
Always make sure to follow the recommendations in your user’s manual before doing any repair work.
- Step 1: Get yourself some penetrating oil spray or MMO (Marvel Mystery Oil);
- Step 2: Keep the part where the spark plug is up and remove the spark plug;
- Step 3: Pour in the penetrating oil or the MMO inside the spark plug hole. Make sure to use enough of the oil or spray and let it sit for a few hours;
- Step 4: Using protective gloves, start manually turning the piston by turning the cutting blade(s).
- Step 5: Once it starts running more smoothly, you can try vacuum pumping the oil in order to get rid of the fine metal particles, then add more MMO or spray and try spinning the engine using the pull cord without the spark plug.
If you want to find out more, make sure to check out this awesome video from Project Farm:
Will Running a Lawn Mower Without Oil Permanently Damage It?
Just because your lawn mower have been running without oil for a very brief period of time does not necessarily mean it is damaged beyond repair.
Your mileage will vary; however, the odds are not in your favor. The damage which the mower will sustain can range from very minor to beyond repair.
Sometimes seized up lawn mowers can be repaired, but they will most likely never perform at the same level as before.
How to Tell If the Engine of a Lawn Mower Has Seized Up?
It is very easy to tell if your lawn mower’s engine has seized up. Here are a few dead-giveaways:
- The lawn mower does not start, and you hear loud knocking and clanking noises; and
- If you try to turn the cutting blade(s), they do not budge easily or at all.
It is advisable to check the spark plug and the oil levels, but usually the two signs above are all you need to know.
If you proceed and open the engine, you will most likely see charred areas and damaged parts of the piston and the cylinder bore. If you try to turn the piston manually, it will be either very hard to move or totally stuck in there.