How to change your lawnmower oil

How to change your lawnmower oil

Michael, Professional and passionate welder, Sheffield

Guide written by:

Michael, Professional and passionate welder, Sheffield

73 guides

An essential part of lawnmower maintenance, your engine oil should be changed every 50 hours of operation, or once a year. The old oil needs to be drained before the new oil is added and you'll need a range of tools, including an oil pan, funnel and a set of spanners. Read on for our handy guide.

Important features

  • Operating hours
  • Oil pump
  • Engine oil
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Why change your lawnmower oil?


In order to ensure your petrol lawnmower has a long lifespan, it is essential to keep it in perfect working order. Among one of the most important steps to achieve this is to change the oil on a regular basis. Depending on how often you mow and the number of overall operating hours, the engine oil will eventually become sticky, losing its ability to coat and protect all the moving parts. As such, it must be replaced. Manufacturers generally recommend draining the oil every fifty hours of use. If you haven't kept track of the time, you should do this at least once a year, either when you are storing your mower for the winter or before the first use of the year. Want to find out how to go about changing your mower oil? Read on for all the steps you'll need to follow.

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Engine oil

Tools and accessories for draining a lawnmower

Most lawnmowers are equipped with a drain plug located beneath the deck. This is very practical, as you simply have to unscrew it to drain the oil. For other models, there is no choice but to tilt the lawnmower in order to drain it.

List of required tools and accessories

  • Oil removal pump (manual or electric)
  • Funnel
  • Measuring cup
  • Mower jack for heavy or bulky machines
  • Set of open-ended spanners or socket set
  • Oil filter wrench (if there is a filter)
  • Oil filter
  • Oil pan with spout for transfer into recycling can
  • Waste can for used oil (designed for waste disposal)
  • Protective gloves
  • Engine oil (see manufacturer's instructions)
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Changing your lawnmower oil in 10 steps

To start with, if the mower you're hoping to drain is cold, you will need to let it run for a few minutes to heat up and thin out the engine oil. This will make it easier to extract. Bring the mower to an open area covered with newspapers or sand to deal with any potential oil leakage.

Draining a mower with a drain plug under the deck


  1. Tilt the mower.
  2. Disconnect the spark plug for safety.
  3. Do not spin the mower blade with your hand. If there is compression in the piston, the blade could still turn and injure you.
  4. Locate the drain plug. After placing an oil pan beneath it, unscrew it with a spanner.
  5. Let the old oil drain out.
  6. Re-insert the drain plug. If you notice that the seal is worn or unusually flat, replace it.
  7. If the mower is equipped with an oil filter, disassemble it with the filter wrench and replace it.
  8. After placing the mower back on the ground, fill the oil tank with the amount recommended by the manufacturer.
  9. Close the cap, reconnect the spark plug, and start the mower, which should then be left running for several minutes. 
  10. Check the oil level again and top up if necessary. The mower is then ready to use.

Draining a mower without a lower drain plug


Some lawnmowers are not equipped with a lower drain plug. In this case, the process is trickier as you will have to turn over the mower to change the oil. If your lawn mower is too heavy, use a jack.

An oil removal pump may not be the first tool that comes to mind, yet this great accessory will make draining your mower far easier. These tools may be manual or electric and are not expensive. If using the conventional method, your mower must be tilted far back to drain all of the oil. However, if you tilt the mower too far, the oil may enter the piston and leak into the exhaust. If this does happen, don't panic! When the mower restarts, a large cloud of smoke will appear but it will be released after the mower is run for a few minutes. However, you will avoid this issue entirely if you use the oil pump.

Once the oil tank is empty, re-fill it using the best type of oil for the machine. Make sure not to exceed the level indicated by the manufacturer and don't forget to replace the oil filter, if the mower is equipped with one.

If you put in too much oil, the only solution is to drain the excess. Too much oil can cause overheating in the engine and ineffective lubrication of the moving parts. This, in turn, can result in serious engine damage. Remember to re-insert the upper drain plug once you're done.

Disposing of old oil

Any container with old oil, dirty sand or oil-soaked newspapers should be brought to an appropriate waste collection centre for recycling.

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More information

For more advice on gardening equipement, check out the following guides:

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Guide written by:

Michael, Professional and passionate welder, Sheffield, 73 guides

Michael, Professional and passionate welder, Sheffield

I was trained as a pipe worker and a pipe-welder and after having traveled for 35 years working around the UK, I became the head a metal shop and then a designer and in the end the head engineer. I have designed and built a workshop where I make metal sculptures: I managed to find a piece of paradise where I can to let my imagination run wild. Auctions and garage sales are no secret to me. I find unusual objects and old tools there that I collect or transform into works of art. I also like decoration, painting on canvas, and gardening. I am developing new technologies concerning tools. To share my passion and humbly advise you in your choice of materials is a real pleasure.

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