What Happens If You Don’t Change Oil in Lawn Mower

oil check on lawn mower

Since most small motors are designed with no oil filter, dirt from combustion and intake dust build up and degrade the oil and its lubricity. Then, the dirty old oil starts performing its functions less effectively and requires a change to bring back the lawn mower to its full and efficient capacity. But, what happens if you don’t change this oil?

Despite the fancy advertising, no oil lasts more than a year as its functional properties are exhausted. The degraded oil allows for increased wear within the engine parts, and eventually, results in permanent damage when the engine seizes.

Considering this potential harm, how soon should you change your oil? What oil should you use? How long can the engine run before permanent damages? Let’s delve into the simple 30-minute maintenance service that could save you from replacing your mower or make it last years.


Do You Really Need to Change Lawn Mower Oil?

Due to the numerous heated and continuously moving parts, internal combustion engines are reliant on lubrication to ensure they continue to work without tearing apart or grinding to a halt. Once your lawn mower is oiled, its efficiency improves, its lifespan extends, and you deal with fewer repair costs.

Simple engines, no matter how small, such as those in lawn mowers, feature many moving parts designed to operate at very high speeds and temperatures. Changing the oil in your lawn mower ensures you get rid of dirt and debris, which slow down and ruin your engine. It is therefore paramount that you follow the manufacturer’s guidelines when it comes to oiling your lawn mower.


Why Should You Change Your Lawn Mower Oil?

Changing the oil in your lawn mower is a fulfilling project for anyone who loves getting hands-on. However, it shouldn’t be the only reason you take a moment to care for your mower. There are numerous reasons you should change your oil following the defined hours of usage for change or change in season. Here are some benefits of doing so:


  1. The most important function of oiling your lawn mower’s engine is the protection of the engine’s parts. Indeed, there are numerous moving parts in your lawn mower’s engine that need lubrication to prevent wear and tear. Old oil following normal engine wear and tear can easily result in damaged engine parts, reduced fuel efficiency, and even trigger the breakdown of your lawn mower’s engine.
  2. Lengthened engine life. By keeping your lawn mower’s engine clean and protected by clearing off dirty oil, you ensure your device will be running smoothly for years to come. Investing in scheduled and regular oil changes saves you from having to replace the whole lawn mower every now and then.
  3. Clean your engine. As oil flows through your lawn mower’s engine, dirt and other particles, like soot, accumulate in it. If you don’t change the oil in proper intervals, sludge builds up in your engine. Changing oil helps get rid of the harmful bits of dirt and debris before they do any major damage.


When Change the Oil in Your Lawn Mower?

Considering you are out for the best performance of your lawn mower, changing oil is an essential undertaking that works best scheduled, regularly, and following the manufacturer’s guidelines.

To ensure the lawn mower’s reliable and long-lasting service, replace the oil and oil filters (if your mower contains any) at least once during every mowing season or after about 50 hours of use. This applies to when the manufacturer does not provide details. Otherwise, the owner’s manual provides guidelines specific to your model.

You should also keep track of your oil levels using the dipstick, a reliable way to ensure you always have clean and sufficient amounts of oil in your mower. Overfilling the oil in a bid to ensure you don’t have to refill it regularly is one good way to ruin your engine. The excess oil may drown the crankcase or cause the engine to overheat. Although it isn’t as bad as having bad oil, it continuously affects your engine.


How to Know If Your Lawn Mower Needs Oil?

Lawn mowers burn oil much more quickly than cars. If you’re cutting tall or wet grass, make sure you are using even more oil. Most manufacturers recommend checking your oil regularly to ensure your lawn mower is always running efficiently and with a cold engine.

A cold engine is one whereby you’ve let the engine time to drain oil into the crankcase so you can get a better reading of your oil levels. However, the process of checking both the hot and cold engines is generally the same, so no need to worry about the technicalities.

Here is how to check your lawn mower’s engine oil level, whether it does or doesn’t feature dipsticks.


Lawn Mowers with Dipsticks

  1. Start by moving the lawn mower to a leveled area and give it a 10-minute break if it was previously in use. This allows the oil to settle back in the crankcase.
  2. Wipe around the fill tube cap to ensure dirt and grime don’t get into the crankcase once you remove the full tube cap. Use a clean rug, otherwise, you’ll probably end up causing more wear with dirt than you would have experienced by not trying to check the oil.
  3. Turn the cap and remove it from the fill tube. You can wipe the dipstick with a clean rag or tissue to clear off the oil from its surface.
  4. Insert the dipstick back into the fill tube and turn the cap until it locks in place. Turn the cap again and gently pull out the dipstick. Afterward, you can check the oil level on the dipstick. The dipstick is usually notched and labeled to show the high and low levels. The required level is near the upper hole or filling the line on the dipstick.
  5. Top up the oil if necessary, and recheck to ensure you don’t overfill nor add too little. Remember to wipe the dipstick each time you check to make sure you make the correct readings. Once you’re done, replace the cap, lock it, and clean it with a rug.


Lawn Mowers without Dipsticks

Some lawn mowers may not feature a dipstick to help you find out the oil level. This may look like it makes the process tougher, but it is actually much easier to do with such lawn mowers. Here is how it goes:

  1. Wipe the area around the cap with a clean rug, as with all openings to the engine components.
  2. Remove the cap without breaking the mechanism. On engines featuring a dipstick, this piece is attached to the cap, which rotates into a groove to lock. This may simply be a pop-off and on the cap.
  3. Check the oil level in the fill hole. The oil should be near or at the top of a slot used to indicate the highest level.
  4. Top up the oil until it is at the same level as the top of the slot, replace the fill cap, and lock to ensure no dust nor dirt gets in.


How to Change Oil in a Lawn Mower?

Now that you’ve checked your oil level and have discovered it needs a change, how do you go about it? Do you siphon it out or is there some special machine to do it? Well, the process is fulfilling for some as a weekend activity but requires a bit of hands-on.


The tools you’re going to need are:

  • Some newspapers or plastic sheets to cover the work area.
  • A socket wrench or spanner fitting the drain plug
  • A spark plug wrench
  • A shallow container for the drained oil
  • Some pieces of cloth for cleaning up
  • Bricks or some timber to raise the lawn mower off the ground.


  1. Find some open or sizable area, like the floor of your garage or your driveway.
  2. Place the protective materials, such as newspapers, to ease the cleaning once you are done.
  3. Run the lawn mower for some time to warm up the oil. This makes the oil less viscous and more fluid so you can drain it more easily. Do this to drain the gas tank as well so there won’t be any spills while you work on the lawn mower. About 15 minutes of warming should do the trick, so add just a little amount of fuel to run for that short time.
  4. Shut down the engine and disconnect the spark plug. This ideally ensures the engine doesn’t start, should you mistakenly turn the blade.
  5. Drain the old oil into a container. It may require you to simply unscrewing an oil drain plug on the underside of the sump or tilting the lawn mower and draining it through the oil fill plug. Check the instructions from your manufacturer’s guide to ensure you use the recommended draining method.
  6. Place the drain plug back, remembering to tighten it right, but not too tight, as you could split it if it is plastic or ruin the thread on the sump if it is metallic.
  7. Make sure you use a funnel to channel the oil without making a mess when you add the recommended type and amount of oil.


What Oil Should You Use for Your Lawn Mower?

Different manufacturers usually recommend specific oil types for their products depending on the engine’s size and technology. However, some general specifications can help you out in case you are in limbo. The following are some guidelines to help out.

If you have a small or medium-sized mower, you will probably need about 17 to 20 ounces (500 to 600 mL) of oil, depending on the measurements used in your region. For most engines, SAE 30 or 10W30 multigrade oil efficiently supports their running. For the larger engines, you may have to use 15W40, which is more viscous when hot.


Changing Oil for the Winter

One often overlooked practice conducted by lawn mower owners is the de-winterizing process. This involves, among other activities, the changing of oil to ensure the engine’s components do not get ruined over the winter. However, although the process is simple and shouldn’t take more than a day, it extends your lawn mower’s life by multiple years.


The following steps should help ensure your lawn mower starts with ease after winter ends:

  1. Change your oil. After the mowing season, your old oil is full of soot, gasoline, moisture, and acids, which can corrode the engine’s components over the winter. Thus, change your oil and run the lawn mower for a few minutes to coat the components with clean coats of oil.
  2. Drain or brim your gas following your manufacturer’s instructions. The leftover gas could corrode your carburetor or clog the fuel system. Follow the model’s manual as some manufacturers recommend completely filling up with fresh, stabilized gasoline.


*Add fresh stabilized fuel – Don’t add stabilizer to old fuel as it won’t bring it back to life. A stabilizer should be added to fresh gas instead. The process is simple. Add fuel stabilizer to an empty fuel can. Add fresh fuel and thoroughly mix the stabilizer into the fuel. Fill the lawn mower with this gas to ensure the fuel filling the carburetor bowl is stabilized gas. You can then top off the gas tank and store the mower.


What Happens If You Run Your Mower Without Oil?

While you regularly need to refill your lawn mower’s gas tank, oil never comes up in one’s mind. It is reliant on a schedule or change in season and might sometimes not be the most reliable way to keep your engine healthy, as you might easily forget or get held up on other activities like work, shopping, or traveling. So, what happens if your lawn mower runs out of oil?

Oil is an essential part of all engines, whether large or small. Its key function is to keep the moving parts lubricated to reduce friction between them and keep the engine’s temperatures under control. If the engine oil runs out, friction between the moving parts of the engine will increase, causing overheating, fusing of pistons, and seizing of the engine. This damage is almost always irreversible.

Since most lawn mowers are made as simple as possible, they will even start without oil, and you’d be very lucky to notice any problem early on. If it’s dirty and contains old oil, you can replace it. And if it’s fresh but finished, you can simply top it up. Unusual noises and engine knocks are signs you need to do some repairs as some damages have already been done.


How to Know If Your Engine Has Seized?

After running a mower and hearing noises and the mower turning off on its own, cross your fingers because you could have caused your engine to seize. In this case, pull the starter cord. If it is moving, the engine is turning, and thus, the mower is still good. This is, however, not foolproof as sometimes the engine will not seize until it has cooled down.

Another way to check if the engine has seized is to try and turn the cutting blade. Make sure to take out the spark plug first lest you lose a finger or two. If it turns, the engine is still good. On the other hand, if it is jammed in place, start budgeting for a new mower.


How Long Can Your Lawn Mower Run Without Oil?

Domestic lawn mowers seize quicker as they sit for long periods between uses. Thus, the oil settles in the sump. The difference is however negligible as both commercial and domestic mowers will seize up in less than five minutes.

If you are lucky enough to notice and shut it down before the engine seizes, top up the oil before it cools and seizes up. This is, however, not reliable, and most times, the engine seizes up as it cools anyway. One thing to note is that lawn mowers will not smoke due to having too little oil. Smoke is caused by the lawn mower burning off excess oil, hence why low oil levels will not cause smoke emission.


Will Your Lawn Mower Automatically Shut Down Because of Low Oil Levels?

Considering most lawn mowers do not have an oil switch, they do not automatically shut down. The more modern models, however, may have a switch to ensure damage is prevented by low oil levels. However, it should only back up your regular oil maintenance practice. This will ensure you also run on clean oil, which in turn, ensures you enjoy your lawn mower much longer.

Your lawn mower’s engine may start even if you have zero oil in it. While the newer models are designed not to start if their oil checking mechanism fails, most models will start. You’ll probably hear a knocking noise right on start up, which will give you a very short window to shut it down and prevent any irreparable damage.

Once your engine seizes up, your chances of repairing this damage are very slim and costly. You may even shut it down in time but have it seize as it cools. The damage usually consists of parts fuse rendering the engine into a hunk of pretty much worthless metal. Disassembly and lubrication are a good trial, although, for the most part, the lawn mower is usually a write-off.

All machines with moving parts, from bicycle gears to motorized engines or sewing machines, need oil to ensure the parts do not grind to piles of metallic ash. A lawn mower is no different despite its compact size. It is, therefore, good practice to follow a schedule and constantly check the oil levels before and after prolonged use to ensure you do the minimum, if any, intentional damage to it.

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