How to Change Oil in a Lawn Mower

Updated on April 26, 2018
eugbug profile image

Eugene has a keen interest in DIY and gardening. Over a 30 year period he has also become self taught in garden power tool maintenance.

Source

Maintaining Your Lawn Mower Engine

Motor oil is an essential requirement of all engines. It has several functions including lubrication of metal parts in contact (reducing friction), cooling, keeping surfaces clean, sealing and corrosion inhibition.
Your 4-stroke walk behind lawn mower engine is no different. The oil inside it gets dirty over time and without an oil filter to remove metal particles and soot, these contaminants can build up over time and cause engine wear. So it is a good policy to give it an oil change after every 20 to 50 hours of use (consult the manual of check the engine block for exact details).


Safety First While Working on a Lawn Mower

  • Don't run a lawn mower in an enclosed space. Carbon monoxide gas which is present in exhaust fumes is odourless, colourless and tasteless, but poisonous and can kill. Ideally run a mower outdoors when testing. If the mower is run in a garage/workshop, it should only be operated for a short period and you must ensure all doors and windows are open in order to provide adequate ventilation.
  • Set controls to off and remove the spark plug lead before working on any moving parts on an engine e.g. the blade. Ideally you should also remove the spark plug to be totally sure that the engine won't fire if you turn the blade.
  • Keep gas away from any sources of ignition.

What Tools are Required to Change Oil?

  • Socket wrench set
  • Spark plug wrench
  • Shallow container for collecting drained oil. A biscuit (cookie) tin is ideal
  • Some cloths for mopping spillage and wiping hands
  • Disposable gloves
  • Some newspapers/plastic sheeting for covering the floor or ground surface
  • Bricks or short pieces of 2" timber for raising the mower off the ground

A shallow tin like this one is ideal for draining oil into. Metal tins aren't totally leak proof and oil will eventually ooze out, so dispose of it safely
A shallow tin like this one is ideal for draining oil into. Metal tins aren't totally leak proof and oil will eventually ooze out, so dispose of it safely | Source

Step 1: Find a Location

Pick a suitable location for working on, ideally the concrete floor of your garage, or you can work outdoors on a driveway.

Step 2: Keep Your Working Area Clean!

To avoid mess, cover the working surface with a few newspapers, plastic sheet or refuse sack (trash bag) to collect any drips/spills.

You can use a refuse sack (trash bag) for covering the ground or floor.
You can use a refuse sack (trash bag) for covering the ground or floor. | Source
Cover the floor with a refuse sack (trash bag), newspapers, plastic sheet etc.
Cover the floor with a refuse sack (trash bag), newspapers, plastic sheet etc. | Source

Step 3: Add A Little Fuel to the Lawn Mower Tank

Pour a small amount of gas into the tank, enough to allow it to run, so that it doesn't leak out when you turn the mower on its side. Alternatively drain gas after running the engine.

Step 4: Run the Engine to Warm the Oil

Run the engine for about 5 minutes to warm up the oil. This makes it less viscous and more fluid and it will drain easier. Don't run it any longer than this or the oil will scald you if it gets on your hands while draining!

Step 5: Remove the Spark Lead

Detach the spark plug lead and ideally remove the spark plug from the engine to prevent it starting.

Step 7: Decide Whether to Drain Through the Plug or the Oil Fill

The oil in a 4-stroke engine is held in a reservoir at the lowest point called the sump. Usually an oil drain plug is screwed into the underside of the sump and when this is removed, oil can be easily drained. Any sludge which has settled should drain also. Not all engines have a drain plug and oil must be drained from the oil fill plug by tipping the mower on its side.

Step 6: Lay the Mower on Its Side

If you decide to empty the oil through the drain plug, place the engine on its side. Usually you need to keep the carburetor side of the engine uppermost to avoid oil leaking out through the breather. However check this out first.

Usually you need to keep the carburetor side of the engine upright to avoid an oil leak when you turn the blade
Usually you need to keep the carburetor side of the engine upright to avoid an oil leak when you turn the blade | Source
The breather, a vent to the oil containing sump on the underside of the engine, is usually on the side of the engine adjacent to the air filter and carburetor. Keep it upright to avoid an oil leak
The breather, a vent to the oil containing sump on the underside of the engine, is usually on the side of the engine adjacent to the air filter and carburetor. Keep it upright to avoid an oil leak

Step 8: Locate the Drain Plug

Locate the drain plug. This may look like the hex head of a bolt in which case you can loosen it with a socket wrench. If you don't have a socket set, you can use an open ended wrench (spanner). Alternatively the plug may have a square head and you will need to use an open ended wrench. Some plugs are recessed and flush with the sump with a hex socket or square socket head, requiring an Allen key or the 1/2 inch drive of a socket wrench respectively to be loosened. Turn the blade of the mower to move it out of the way if it is obstructing access. Alternatively remove it. In general the bolt which fastens a lawn mower blade in place is loosened by turning it counter-clockwise.

Source
Oil Drain Plug
Oil Drain Plug | Source

Step 9: Loosen the Drain Plug

Loosen the plug, but don't remove it fully. Turn the mower back onto its wheels and position it over the tin. If you raise the cutting height to the highest setting, it may be easier to accommodate the tin under the deck of the mower. You can also raise the front and back wheels onto short slabs of timber or bricks to increase clearance so that you can get your hands under the mower. Just be careful that it doesn't roll off these and drop down onto your hands while removing the drain plug.

You can raise the wheels up on pieces of timber or bricks for added clearance to fit the tin underneath. Roll up your sleeves and wear disposable gloves while draining.
You can raise the wheels up on pieces of timber or bricks for added clearance to fit the tin underneath. Roll up your sleeves and wear disposable gloves while draining. | Source
I drained oil into this tin.....
I drained oil into this tin..... | Source
........and bent a "spout" with a pliers to make it easier to empty the tin.
........and bent a "spout" with a pliers to make it easier to empty the tin. | Source

Step 11: Replace the Drain Plug

Turn the mower back on its side and replace the drain plug. Don't over-tighten it, especially if it is made from plastic. Wipe away any oil from the underside of the deck.

Step 12: Add the Recommended type and Amount of Oil to the Engine

Add the new oil to the engine through the fill plug. A funnel helps to avoid mess.

What Oil Do I Need for a Lawnmower?

Oil is replaced in a mower through the oil filler plug. If the oil bottle has a narrow spout, you can pour it in directly, alternatively use a funnel. For small to medium sized mowers, you need from 17 to 20 fluid ounces (U.S.) or 500 to 600 ml of oil. Usually there are graduations on the side of small bottles of oil so that you can ascertain how much you have poured out. However I find it more convenient to use a plastic milk container which I have placed a mark on the side of, indicating the required amount of oil to fill my mower. I keep this container from year to year and I fill up to the mark from the oil can, and then just empty this amount of oil into the mower.
Generally an SAE 30 or 10W30 multigrade oil is recommended. Sometimes 15W40, which is more viscous when hot is recommended for larger engines. Check your manual for the required quantity and type of oil.

Oil level should be between the high and low mark on the dipstick
Oil level should be between the high and low mark on the dipstick | Source

How Often Does Oil Need to be Changed?

Generally every 50 hours or every season, whichever comes first

© 2013 Eugene Brennan

Comments

    0 of 8192 characters used
    Post Comment

    • eugbug profile image
      Author

      Eugene Brennan 5 years ago from Ireland

      Thanks for dropping by and the comments!

    • wilderness profile image

      Dan Harmon 5 years ago from Boise, Idaho

      This is something that is all to easy to forget, and more than a few people have ruined a mower by never changing the oil at all.

      Good instructions and photos - you've made it easy to follow the instructions.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: "https://dengarden.com/privacy-policy#gdpr"

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)