• Sharpening the blade (very important for keeping your lawn in good condition).
• Changing the spark plug (if this fails your lawnmower won’t start until you change it).
• Changing the air and oil filters.
• Changing the oil.

In this post I’ll cover the general process for changing the oil.  This is really important for keeping the lawnmower running smoothly – imagine what would happen if you never changed the oil in your car!  It wouldn’t be as serious to a lawnmower, but could still cause some damage.

Before I begin, I should again note that you should also read your manual for guidance specific to your lawnmower; ensure that the mower is switched off with the spark plug out; and remember that PetrolLawnmowerSite.com can’t be held responsible for any problems that may be caused by following this advice.

That said, if you’re quite technically competent, this should be a fairly simple job.  It is an extremely dirty job, however, so wear old clothes and do it somewhere you could stand to be stained with oil for a while.

1. You need to buy the correct type of oil for your lawnmower.  A repair shop or the place where you bought your petrol lawnmower should be able to help.  Failing this, the user manual will say, or the manufacturer will almost certainly be able to tell you.
2. It’s always a good idea to care for your tools, so this is a good point to clean all around the oil tank.  In fact, if you have time, giving a good clean to the underside of the lawnmower can also be beneficial – fungus from the lawn can stick to the underside (especially if you mowed the grass when it was wet).  By cleaning this regularly, you decrease the risk of continually spreading the fungus around your lawn.
3. If the oil tank has an attached dip stick, remove this.  If not, you’ll need to ensure you have one available.
4. On the bottom of the oil tank there should be a plug to drain the oil.  If you unscrew this, the oil will drain out immediately, so ensure you have something underneath ready to catch the oil.  If the plug is connected too tightly, use a wrench to loosen it.
5. After draining the oil, screw the plug back into it’s slot.  (Do not just pour the old oil away because this is harmful to the environment.  In most European countries and in the US, there will be specific places in the local neighbourhood to dispose of oil.)
6. Now you should replace the oil by removing the cap at the top of the oil tank and filling the tank back up to the correct level (use the dip stick to check this).
7. Replace the dip stick and reconnect the cap on top of the oil tank.
8. Then simply reconnect the spark plug and start up the lawnmower.  It’s always a good idea to let the lawnmower sit whilst switched on for a few minutes so you can visually inspect it and check that there’s no leaking oil.

And that’s all there is to it.  If you have any advice or tips on changing the oil on different brands of lawnmower, please leave them in the comments.

Note: The image is for illustration only; your lawnmower may look different.

This means that it’s important to keep the blade sharp to ensure the grass is cut properly. If you’re using a petrol lawnmower professionally, you may want to sharpen the blade as often as once a month. If you’re not a professional landscaper, and just use the lawnmower for home use, you can afford to sharpen the blade less often. You can check if the blade is due to be sharpened by looking at the lawn when it’s been freshly mown. Is the grass nice and evenly cut, or is it ripped and jagged? If it’s the latter, it’s time to sharpen the blade.

Warning: This is a fairly straightforward task for people who have a bit of a handy-man talent. However, if you aren’t confident in following this process, take the mower to a repair shop to have the job done. Neither PetrolLawnmowerSite.com, nor myself can take any responsibility for any injuries or other problems resulting from you following any advice on this website. The onus is on you to ensure you follow all necessary safety precautions and you don’t injure yourself or anyone else.

OK, so with that out of the way, here are some general guidelines to follow:

1. Switch off the lawnmower and take out the spark plug. Never turn over the lawnmower when it’s switched on!
2. Using a wrench, twist the nut that holds the blade in place. When this has been removed, you should be able to pull off the blade.
3. Clean the blade by using iron wool to remove dirt and rust.
4. To actually sharpen the blade, it’s often best to use a grinding wheel if you have access to one. Again, if you’re using this, follow all necessary safety precautions. If you don’t have access to a grinding wheel, using a file should do the job nicely. (Your lawnmower may have come with an included kit for sharpening the blade; if so, just use the kit.)
5. For the lawnmower to cut the lawn as evenly and well as it can, the blade needs to be balanced. If you’ve sharpened more on one side than the other, it will lose its balance. To check for this, hold the blade at its centre and see if it leans more to one side than the other. If so, sharpen the heavier side a small amount more until the blade is properly balanced.

That’s the general process and should work with most petrol lawnmowers. However, you should also read the lawnmower’s manual and check for any advice specific to your model of lawnmower.