How to Change Lawn Mower Oil. Lawn mower motor oil

How to Change Lawn Mower Oil

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This article and its video explain how to change lawn mower oil on most mowers, and how to change oil filters on mowers that have them.

The small engines that run lawn mowers need their oil changed just like car engines. Most mower engines need their oil changed every 20-50 hours of operation.

A mower’s owner’s manual will indicate how often to perform oil changes on the mower. At the very least, an oil change should be done annually with other seasonal tune-up maintenance.

This article explains the steps for changing oil in most mowers. Changing mower oil is very simple and can take as little as five minutes.

Step 1: Prepare for the Oil Change

Warm up the engine

Warming up the mower engine will speed up the oil change because the oil will flow more freely. It will also be a little easier to get all of the old oil out of the engine.

Clean around the oil fill area.

Use an air compressor or a clean towel to clean up around the oil fill area

Prepare an oil pan to catch the oil.

You’ll need an oil pan or something similar to catch the oil from the mower. Position the pan on the side of the mower towards which you will tip it to drain the oil.

Step 2: Dump the Old Oil

Remove the oil fill cap.

Tip the lawn mower on its side to drain its oil.

It’s a good idea to leave the mower resting on its side for about a minute while all of the old oil drips out.

Step 3: Replace the Oil Filter (if Applicable)

The majority of walk-behind lawn mowers do not have oil filters, but several models on the market include them in the engine design. We’ve included the steps for changing a mower’s oil filter below in case your mower model includes one.

If your lawn mower engine model does not include an oil filter, skip to step Step 10 to complete your oil change.

Prepare something to catch the oil.

Unscrewing your mower’s oil filter will spill the oil it is holding inside of it.

Find something to catch the oil that is small enough to fit under the filter as you unscrew it.

Unscrew the old filter.

The old filter simply unscrews.

Coat the seal of the new filter with oil.

The seal of the new oil filter needs to be coated with oil before it is installed.

Using your finger, apply a small coat of motor oil to the outside lip of the new filter. This thin coat of oil will ensure that it seals tightly when you install it.

Install the new oil filter.

Screw the new oil filter into place until it touches the plate it seals against. Then, give the filter a firm 1/4 or 1/2 turn to tighten it down.

Step 4: Refill Mower Oil

Now the mower is ready to have its engine oil refilled. Remember that over-filling the oil on a lawn mower engine is just as bad as under-filling it.

Check the mower owner’s manual for the exact quantity of oil that the mower takes.

Use the mower’s dipstick as the final judge on the right oil level. Most mowers take between 2/3 and 3/4 a quart of oil

Add engine oil gradually until it is full.

Stop a couple of times as you fill the oil to check its level with the dipstick.

Creeping up on the “full” line like this reduces the chance of overfilling.

Replace oil cap.

Your lawn mower oil change is now complete.

Changing your lawn mower’s oil will help its engine run powerfully and dependably. This and other simple equipment maintenance will greatly extend the life of your tools. can help you with your lawn garden machine repairs. Visit our Lawn Mower Parts page to shop for parts by mower brand, or visit our Small Engine Parts page for more small engine maintenance parts.

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My lawn mower that a friend recently gave me wouldn’t stay on today when I was trying to cut the grass after filling it with gas so I’m assuming it might need an oil change. Now because I’ve never been responsible for the maintenance of a lawnmower prior to now, I’m wondering if I have to drain the gas out first prior to tipping it over?

What about removing the drain plug from under the deck.

Many new mowers no longer have a drain plug under the deck unfortunately.

Funny I spent 10 minutes looking for a drain plug on my self propelled TORO, since my last lawnmower had one under the deck. Well I finally gave up and asked my brother for advice and he suggested exactly what is described in this article. The only drawback with this method is that oil tends to get in the combustion chamber resulting in a puff of smoke (pollution) the next time I start it.

Just want to point out that I hadn’t changed the oil in 4 years since I bought it (don’t know how I forgot as I am usually pretty good) and boy was the oil black and dirty. Had to flush it about 5 times (starting it between changes and letting it run for a minute or two) before the oil started to drain clear. I used synthetic oil as it’s the only oil I use for all my 4 stroke combustion engines.

How to Change the Engine Oil in a Lawn Mower

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Keeping your lawn maintained helps to cut down on insect populations in the yard, builds strong roots for healthier lawns and adds an exceptional amount of curb appeal.

Lawn maintenance begins with a well-maintained lawn mower which means there are certain tasks you need to perform in order to keep the machine in top working order. One of the most important aspects of ownership is knowing how to change your mower’s oil. We’ll take a closer look at that in this article.

Preparation and Setup

Location is important when preparing to change your lawnmower’s oil. You’re going to want to avoid servicing the machine on grass or near flower beds and foliage due to the chance of oil spillage which can kill your plant life. Select a hard, flat surface such as a driveway or sidewalk and be sure to employ a drop cloth to catch any mess that may occur.

Warm oil is better. While it is certainly possible to change the oil in a cold engine, remember that this lubricant becomes more viscous at higher temperatures. A good rule of thumb is to run your mower for a minute or two to heat it up a bit. In doing this, you’ll have much less trouble extracting the old oil. It’s also good to take precautions with handling a warm mower as the likelihood of engine burns increases. It is recommended that you use work gloves to mitigate the risk of injury.

Finally, you will want to remove the spark plug wire from the plug itself and keep it away to avoid any sort of accidental engine start. The last step in your preparation should also include cleaning the area around the oil fill opening as this prevents any outside debris or dirt from entering the oil reservoir.

Removing the Old LawnMower Oil

Extracting the old oil is one of the most important steps in the process. You’ll want to ensure that you remove as much of the old product as possible. Here are three methods to help you do so:

  • Use a siphon: If using a siphon place one end of the tube into the dipstick/oil fill hole until it reaches the bottom of the oil reservoir. Place the other end of the siphon into a structurally sound container that you will specifically use for this and future oil changes. Make a note to use a container that is easy to handle as you will need to transfer your oil into approved containers for proper disposal. Finally, place wood blocks or other sturdy material under the wheels of the mower on the opposite side of the oil fill hole. This helps to remove as much of the oil as possible.
  • Remove the oil plug: Depending on what type of mower you have, you can remove the oil plug to drain out the old lubricant. Refer to your owner’s manual for the location of your drain plug and be sure you have the proper sized socket wrench for the job. Once located, position the plug over your catch container and remove it. When the oil is fully drained, replace the plug securely.
  • Tilt Method: If you do not have access to a siphon, you can drain by tilting the mower on its side. When tilting the mower, position the oil fill cap over the container you are using to collect the used oil. Once positioned correctly, remove the fill cap and let the oil drain completely. You should be aware of the fuel level of the mower when using this method and should only attempt to do so with an empty or near the empty tank to avoid spillage. This method also requires you to make a note of where the air filter is located as you do not want to contaminate it with draining oil.

Fill With New Oil

Now that the old oil has been removed, it’s time to fill your reservoir with fresh lubricant. Once again, refer to your owner’s manual for the approved type of oil for your mower and the proper amount your machine requires. Keep in mind that both over and underfilling your oil reservoir can be harmful to the life of your mower. Fill the oil tank and replace the dipstick cap. Let the oil settle for at least two minutes and then check the level with the dipstick to ensure you have a proper fill.

Final Steps to Change Oil in a Lawnmower

Once you have the oil reservoir filled to the proper level, you will need to place the spark plug wire back on the spark plug. Your used oil is recyclable and most towns and counties have ordinances on proper disposal. You should check with your local government to find out the specifics, but chances are you’ll need to transfer it from a catch pan into a sealable container. Empty household detergent containers are perfect for this – just be sure the oil has cooled before you do this. Seal the cap tightly and bring your oil to a recycling center. Most gas stations and auto repair shops will accept used oil although some will charge a slight fee.

Be sure you change your mower’s oil annually or after 50 hours of use to keep it in top working condition. If your machine has an air filter, you’ll want to change that annually as well (You may need a filter or pipe wrench to remove it).

Congratulations, you now know how to change the oil in a lawnmower!

Choosing the right lawn-mower oil is vital to the longevity and performance of your machine. Read on for in-depth advice on how to find the best oil to keep your mower going for years to come.

By Bob Beacham | Updated Jun 22, 2021 11:34 AM

We may earn revenue from the products available on this page and participate in affiliate programs.

Whether you own a brand-new lawn mower or an older model, keeping it in peak condition requires periodic maintenance. Choosing the correct type of engine oil is a key part of the process and can make a huge difference in how smoothly the engine runs and how long the motor lasts.

With various technologies and compositions to consider, making that choice can be challenging. The following guide is designed to help you find the best oil for lawn mower performance and durability. It covers all machine types from modest walk-behind mowers to powerful ride-on models.

  • BEST 4-STROKE OIL:STP 4 Cycle Oil Formula, Engine Care for Lawnmower
  • BEST BANG FOR THE BUCK:Briggs Stratton 2-Cycle Easy Mix Motor Oil
  • BEST FOR OLDER ENGINES:Pennzoil Platinum High Mileage Full Synthetic Oil
  • BEST FOR COLDER TEMPS:Briggs Stratton SAE 5W-30 Synthetic Motor Oil
  • BEST FOR COMMERCIAL MOWERS:Royal Purple 01030 API-Licensed SAE 30 Synthetic Oil

What to Consider When Choosing the Best Oil for Your Lawn Mower

Lawn-mower oil can be categorized as either four-stroke or two-stroke (or four-cycle and two-cycle). The engines themselves operate quite differently, and the two oil types are in no way interchangeable. Mower oil has a number of variables that impact its suitability for different machines; each variable is discussed in the following section.


Small, lightweight engines like those fitted to chainsaws and gas-powered weed whackers typically use two-stroke oil, as do a number of smaller lawn mowers. The oil is mixed with the gasoline and burns away during operation. The wrong mix causes poor firing, smoking, overheating and, in the worst cases, engine seizure.

Four-stroke oil is found on larger and generally more durable lawn-mower engines, ranging from medium-size walk-behind models to commercial ride-on models. The oil is poured into the crankcase much like the oil in road vehicles is and should be changed periodically (usually once a year).

Both four-stroke and two-stroke oils can be either conventional (also called regular) or synthetic. Conventional lawn-mower oil is made from crude oil, whereas synthetic oil is more refined and blended with other chemicals. Synthetic oil offers superior lubrication for high-performance motors, but it’s almost invariably more expensive, and many lawn-mower engines don’t run fast or hot enough to warrant the additional cost. That said, the quantities involved are modest, so some owners choose to use synthetic oil anyway.


Viscosity or “oil weight” is a term used to describe the thickness of lawn-mower oil. These numbers were established by the Society of Automotive Engineers, and so oils bear the initials SAE. The acronym of SAE-30, for example, is a popular lawn-mower oil.

Oil generally becomes thinner as it gets hotter, so low viscosity (thinner) oils work better at low temperatures and high viscosity oils work better at high temperatures.

However, single-grade types, like the SAE-30 mentioned above, have limited flexibility. The solution: multigrades. A 10W-30 oil is a common example. The “W” represents the low- temperature weight, the other number is the high-temperature weight. Such an oil offers good performance at a range of temperatures; thus multigrades offer a better all-around solution. However, while this can make a big difference to owners of road vehicles, they offer minimal benefit in areas where the temperature during the mowing season remains moderately warm or hot. As a result, single-grade lawn-mower oils remain popular.

Additives and Detergents

Modern lawn-mower oils can be highly engineered lubricants with variations tuned to particular performance aspects. Additives generally FOCUS on protecting engine components from excess wear. They may also be designed to optimize performance in older engines.

Detergents help stop the buildup of sludge and other deposits to reduce wear. They’re generally more effective in commercial mower engines that tend to run hot after extended periods of use.

The precise content of these oils, however, is a closely guarded secret. Beyond trusting the reputation of a particular brand, it’s virtually impossible to verify each manufacturer’s claims.


All lawn-mower oils are derived from fossil fuels, so their eco-friendliness is subjective. Oils made from natural gas are the cleanest burning, but at present something of a rarity. However, there are a couple of things that have an impact on the environmental aspects of these products.

Two-stroke engines tend to produce higher emissions than their four-stroke counterparts. The California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (EPA) limit the use of lawn mowers and other engines that don’t comply with certain standards. Some manufacturers have responded by making their two-stroke engines less polluting, and several comply with CARB and EPA restrictions. In general, four-stroke motors are more environmentally friendly.

Synthetic lawn-mower oil may last longer and produce fewer emissions than conventional oils. It could be argued that if oil needs to be changed less often, then less harm is being done. However, this needs to be weighed against the more intense refining process. Any gains are modest, and there’s little practical difference.

It’s important to dispose of used oil properly. It should never be poured down the drain, and in most areas it’s illegal to do so. An increasing number of towns and cities offer curbside collection, or users can search the Earth911 website for the nearest recycling center.

Our Top Picks

Now that we’ve gone over the technical aspects of the best oil for lawn-mower use, it’s time to look at some practical examples. Each of the following products come from a known and well-respected brand with a reputation for quality products. For Rapid reference we have assigned each one an individual category.

STP 4 Cycle Oil Formula, Engine Care for Lawnmower

STP’s synthetic SAE-30 4 Cycle Oil is designed to offer maximum lubrication in small motors typically found in lawn mowers and lawn tractors. While technically only a single-grade oil, the synthetic element gives it all-weather performance comparable with multigrades.

The formulation contains antioxidants that prevent thermal breakdown, or the deterioration of the oil at high temperatures. It has detergents that reduce the buildup of harmful carbon deposits and a corrosion inhibitor that helps prevent rust when the machine is stored outside the mowing season.

STP 4 Cycle Oil is a great all-rounder that suits a wide range of machines and the majority of mowing conditions. It comes in a convenient 32-ounce bottle and is a competitively priced synthetic oil.

Briggs Stratton 2-Cycle Easy Mix Motor Oil

Briggs Stratton is the world’s largest producer of engines for outdoor equipment and as such has unrivaled experience producing motor oil for lawn mowers and lawn tractors.

The company’s conventional two-stroke oil is a low-smoke “ashless” formula. It contains a fuel stabilizer that ensures almost complete combustion of the mix. The result is that the spark plug isn’t fouled by unburned oil and the engine runs more evenly and cleanly.

Briggs Stratton two-stroke oil comes in a 16-ounce bottle to be mixed with gasoline at a 50:1 ratio. To make things easier, there’s a convenient measuring section built into the top. This is a popular product at a very competitive price.

Husqvarna HP SYNTH 2-CYC OIL 2.6OZ

HP SYNTH 2-CYC OIL comes from Husqvarna, one of Europe’s leading manufacturers of powered garden equipment. It’s designed to cool and protect two-stroke motors, which typically run at much higher revs and considerably hotter than their four-stroke counterparts.

This oil is a semi-synthetic blend and offers many of the performance advantages of full synthetics—but it’s blended with conventional oil for economy. It contains detergents to keep the engine running cleanly and a fuel stabilizer to reduce unburned gases, minimize smoking, and reduce harmful emissions.

HP SYNTH comes as a six-pack of 2.6-ounce bottles. It’s intended for a 50:1 mix, and each small bottle is sufficient for 1 gallon of gasoline.

Pennzoil Platinum High Mileage Full Synthetic Oil

Pennzoil Platinum is a synthetic 5W-30 motor oil primarily designed for use in high-mileage road vehicles. However, those same properties also make it appropriate for older lawn-mower engines that are showing signs of wear.

If an engine starts to get noisy the natural inclination is to use thicker oil to keep it quiet, but this “solution” only masks the problem. Pennzoil Platinum is a patented natural gas–based formula that minimizes friction and doesn’t burn off in worn engines like some petroleum-based alternatives. It also contains detergents to reduce carbon deposits that cause additional friction.

Because it’s intended for vehicle engines, Pennzoil Platinum comes in a larger 5-quart bottle. While the initial cost is higher than many lawn-mower oils, it’s nothing compared to the extended life it can provide.

Briggs Stratton SAE 5W-30 Synthetic Motor Oil

Briggs Stratton’s four-stroke SAE 5W-30 oil is a fully synthetic multigrade that many argue is the optimum weight for all outdoor power equipment. While this oil is recommended for the brand’s own mowers, it can be used in any air-cooled, four-stroke motor.

The 5W low-viscosity element makes it an excellent choice for cooler climates where it flows freely and maintains lubrication. The 30-weight component ensures a good all-around performance in all conditions. In fact, the oil remains efficient in outdoor temperatures anywhere from.20 degrees Fahrenheit to 100 degrees Fahrenheit. It also contains detergents to reduce deposits that cause increased friction and can lead to overheating.

Briggs Stratton SAE 5W-30 comes in a 32-ounce bottle. For a synthetic lawn-mower oil it’s remarkably good value for the price.

Royal Purple 01030 API-Licensed SAE 30 Synthetic Oil

Royal Purple’s SAE 30 four-stroke oil is a high-performance synthetic single-grade designed to maintain efficient lubrication and cooling in motors under consistent heavy load: the kind of conditions commercial lawn mowers often need to endure. It can also be used in diesel engines.

The complex formula offers reduced wear, corrosion protection, and increased efficiency with fuels that contain ethanol. It can improve low-speed firing, helps minimize emissions, and is claimed to reduce fuel consumption.

Royal Purple four-stroke oil comes in various sizes from 1 quart to 5 gallons, allowing commercial mower owners to make the most economical choice for their equipment size.

FAQs About Oil for Lawn Mowers

The information above should have left you better informed about how to choose the best oil for lawn-mower maintenance. While important technical and performance issues were covered, there are a few practical considerations that may raise questions. Here are a few answers to the most common questions about lawn-mower oil.

Q. How often should the oil be changed?

Two-stroke oil changes constantly because it’s mixed with the gasoline, so there’s no need to worry with that type of mower. Four-stroke mowers need more regular attention, and there is a useful article on maintenance here. It suggests keeping an eye on oil level and topping up periodically. A full change is usually only necessary once per season or for small mowers every 50 hours. For riding mowers, an oil change every 100 hours is recommended.

Q. How do I change the oil in the lawn mower?

Instructions will be provided with your new mower and should be followed carefully. Generally there’s a drain plug in the crankcase which is removed, and the old oil is collected in a tray or a pan. Tipping the mower will help ensure it’s empty. Larger mowers may have an oil filter that needs to be replaced. Once that’s done, replace the drain plug and fill with the required quantity of new oil.

Q. How much oil should I use for a lawn mower?

The manufacturer will recommend the quantity, and it’s important to be as accurate as possible. Overfilling can cause as much harm as underfilling. Using a plastic measuring jug is a good idea. Small mowers take anywhere from 15 to 24 ounces of oil, while riding mowers will need 48 to 64 ounces.

Q. Is there any difference between a four-cycle oil and a regular one?

“Regular oil” is usually a term associated with those made from crude oil rather than synthetics. Both four-cycle and two-cycle oils come in either form. The information above should help you decide which is best for your lawn mower.

Q. Can I use my motor vehicle engine oil in my lawn mower?

Often you can use motor oil on large ride-on mowers and older machines. It’s important to check manufacturer recommendations. For walk-behind models, it’s usually better to use small engine lawn-mower oils which are specifically formulated for the performance of these types of motors.

Q. What happens if I don’t change my lawn-mower oil?

Dirt and carbon will accumulate in the oil, causing a higher wear rate of engine components. The oil itself will degrade and the engine will overheat, which can result in engine failure or it may dramatically shorten the life of the mower.

Lawn mower motor oil

A question we commonly receive is “what type of oil should I put in my lawn mower?” In this article, we’ll go over the different types, what the numbers actually mean, and compare conventional to synthetic oils.

Changing the Oil

The internal combustion engine in your lawn mower needs oil in order to run. Without it, your engine would overheat and seize up, as the oil helps to lubricate all the moving parts. Dirty oil will wear the engine faster, decreasing its lifespan. Changing the oil in your lawn mower is an important part of its routine maintenance, and should be done at least once per season, or every 50 hours of use. Proper oil changes can increase your mowers performance and add years to its life, which will save you money in the long run.

How to Read the Labels

An SAE number is a code used to classify oil by viscosity, which was developed by the Society of Automotive Engineers. Viscosity is a measure of a fluid’s resistance to flow, sometimes referred to as the “thickness” of a liquid. The lower the number the easier the liquid flows. Motor oils have a rating between 5 and 50. Temperature can make a difference in a liquid’s viscosity, which is why the different oils have ratings for winter, indicated by the “W”. Oils that are multi-rated (for example, 10W-30) can be used in both summer and winter temperatures since the oil won’t thicken in the cooler temperatures due to additives.

Different Types of Oil

So, what type of oil should you use for your lawn mower? One factor to keep in mind is the climate for where you’re located. Different oils work best at different temperatures, and they won’t all be right for your equipment. Always be sure to check your owner’s manual for the manufacturer’s recommendation for your mower. We’ve put together this guide to help you choose between some common types of oil.

SAE-30 Small Engine Oil

This is the most commonly used grade of oil for lawn mowers since it is ideal for temperatures between 40 to 100 degrees Fahrenheit (4 – 37C). If it’s cooler than 40 degrees outside, you probably don’t need to be mowing your lawn. Overall, this is your best bet for an inexpensive oil you can use in your lawn mower from spring through to fall.

SAE 10W-30

This oil has a wider range of temperatures that it will work for, from 0 degrees to 100 degrees Fahrenheit (-17 – 37C). Because it can handle cooler temperatures, this type of oil can also be used in other small engines like snow blowers. If used when temperatures are above 80 degrees, you may find your mower increases the oil consumption.

SAE 5W-30

This grade of oil performs best in temperatures below 40 degrees Fahrenheit (4C). So, it is ideal for your snowblower, but not a good choice for your lawn mower.

Synthetic SAE 5W-30

The synthetic version of 5W-30 has a wide range of temperatures it can be used in, from –20 to 120 degrees Fahrenheit (-28 – 48C) so it works year-round for your small engines. It improves the starting of your engine, and reduces oil consumption, but it is more expensive to purchase.

Synthetic SAE 15W-50

This oil also has a high temperature range, from 20 to 130 degrees Fahrenheit (-6 – 54C) but performs best in higher temperatures. It is typically used for commercial lawn cutting equipment.

Conventional Oil vs Synthetic Oil

Is conventional oil or synthetic oil better for your engine? Generally speaking, conventional oil will work just fine in your small engine. So long as you are using the oil under proper conditions, it will provide the protection and lubrication your mower needs at an affordable price. Synthetic oil however offers more protection, at a wider range of temperatures, but that comes with a higher price tag. The synthetic oil does collect more dirt, so when changing the oil these particles will be removed from your mower. This can lead to better performance overall. Whichever option you choose, it’s important to check and top up the oil levels throughout the mowing season, and to change it out completely after approximately 50 hours of run time.

A well maintained and cared for lawn mower will perform the most efficiently, saving you money in the long run. If you need genuine OEM replacement parts for your lawn equipment, you can find them by searching for your model number on Be sure to follow along and subscribe to our YouTube channel so you don’t miss any tips!

Comprised of creative, experienced video producers, writers, and graphic designers, the Content Team is focused on using their diverse knowledge base to create high-quality informative content to achieve our simple mission: Help the world fix things. Whether it be through tips, guides, or hacks, we ensure that every piece of content includes only expert knowledge, to guarantee that you can do the job right the first time!

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