A lawn mower motor is like any other motor in that it needs lubrication to run properly. Just like your car, running the motor with no oil or low oil can be harmful to your mower and quickly destroy it. That’s why it’s a good idea to learn the signs and symptoms of low oil in your mower. So without further ado, I’ll run through a few signs your lawn mower needs oil and what to look for, as well as explain what to do if you notice them.
Symptoms of a Lawn Mower with Low Oil
Running your mower with low oil or without oil can create a lot of damage very quickly. You may wonder: Will low oil cause my lawn mower not to start? The answer is usually no, and that makes the situation worse because you may start it and cause damage. You should always check the oil using the dipstick before starting the mower, but if you (like me on many occasions) have forgotten to check, you’ll want to know how to tell if it’s low on oil by looking at how the mower functions when running.
Signs your mower is low on oil:
- Noise (lawn mower engine knocking, sputtering, rough idle)
- Mower overheating
- Smoke (this could be a bad sign)
- Mower stops running (this is a VERY bad sign)
Common Signs Your Lawn Mower Needs Oil
If you forgot to check the oil dipstick before starting your mower, don’t feel bad. It is a common thing to overlook. If you experience any of these signs of low oil in your lawn mower, you’ll want to turn it off right away.
If you start your mower and the engine is immediately making knocking noises, or some other type of rough sound, you should turn it off right away. You may prevent serious damage if you turn it off quickly enough. If the noise was caused by low oil, or worse, no oil, you only have a small window of time to run the engine before it starts destroying itself.
If you can tell your lawn mower is overheating, this is a problem. If the mower is throwing off a lot of heat, chances are it has already been running too long without oil and is breaking down on the inside. This could be melting seals and causing the metal inside the engine to change shape which increases damage.
You may ask yourself: Will my lawn mower smoke if it is low on oil? The short answer is: It could. But this doesn’t always mean low oil.
If smoke is coming from the engine, this could mean there is either not enough or too much oil. The first one is a much worse problem. Running it with low oil and seeing smoke means that the internal parts of the engine have heated up to the point of creating smoke. This happens when low oil leads to increased friction inside the mower.
Side Note: One other thing to keep in mind is if there is too much oil in the mower, you may see smoke in the form of burning oil. This is usually a bright white or blue colored smoke. This can also be damaging to the mower, but you won’t destroy it right away by running it. Another symptom of too much oil could be that you see oil coming out of the exhaust.
Mower Stops Running
This is usually a result of severe damage inside the engine. If you noticed any of the other signs and then your mower shuts itself off, the friction inside the mower may have created so much heat that the moving parts seized up. It is unlikely that your mower will run again. However, if you check the oil after this happens and there is oil inside, there may have been another problem, and hopefully it was less serious.
Why it is Important to Add Oil if You Spot These Signs
If you have started your mower without checking the dipstick and you notice any of the signs the mower needs oil, it would be best to turn it off as soon as possible. Worst case scenario, if there is no oil in the motor, you may have a window of about a minute before the damage inside becomes irreversible. The mower will probably sound very rough, and you will certainly notice something’s wrong!
Engine Seizes Up
This would be the worst thing to happen after running your mower with low oil. The engine will create so much heat that the metal pistons will begin to deform, and they will not be able to move smoothly within the engine anymore. You might as well begin looking for a new lawn mower if this happens.
Destruction of Internal Seals
The excess heat created by the engine without oil will cause seals and gaskets within the engine to melt. These seals are essential to keep the process of combustion controlled and to keep the oil within the engine. If they become melted, you will quickly lose all the oil in the engine, and it will stop creating power. Luckily, these seals can be replaced.
Wear of Other Internal Parts
The main purpose of the oil in the engine is to reduce the friction caused by metal parts moving at high speeds. Without the oil, these metal parts are sliding against each other with no barrier of lubrication, and this will cause grinding, scratching, and possibly breakage of small pieces of metal in the engine. These small pieces or burrs that have broken off will quickly grind up the precision metal parts. These parts are engineered to be perfectly smooth and cut to the perfect shape and size to cope with the extremely high velocities and pressures that they will deal with. When they become scratched, broken, or worn out, the engine cannot continue to function the way it was intended to.
Overheating or Fire
This is another worst-case situation, and it will probably also spell the death of your mower. It can also be dangerous. If you run the mower without oil long enough to overheat severely, there is the chance that the mower could catch fire. It is always better to be safe and turn off the mower immediately if you notice any symptoms such as excess noise, smoke, or excess heat coming from the mower.
Some Advice on Adding Oil to Your Mower
If you have any of the signs of low oil in your mower, you will need to add some. It is best to find out which oil is recommended by the manufacturer of your mower, but in a pinch, you may be able to use oil that you have laying around.
Types of Oil
Most mowers are best run with an SAE-30 oil. You may use 5w-30, and 10w-30 as well, if you have one of those on hand. The 10w-30 will be best to use during warmer times of the year, and the 5w-30 can help make a mower easier to start if the temperatures are colder. You may wonder can you use car oil in a lawn mower? As long as the 2nd number in the rating matches the recommended oil weight, you may be just fine using the oil.
Oil Ratings Explained
The first number is the flow rate at the ambient temperature outside of the engine. The lower the number, the thinner it will be. A thinner oil can make it easier to start in the cold months of the year. The second number is the thickness of the oil at operating temperature. This is where the lubrication is most important, as the engine will often be running at full throttle. For this reason, if your mower manufacturer specifies that you need SAE-30, you will always want to use an oil with an operating flow rate of 30. As mentioned earlier, it will always be best to use exactly what is recommended by the manufacturer. In some cases, using the wrong oil may void the warranty.