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How often should I change the spark plug and oil in my lawn mower?

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  • Jun 23rd, 2010 6:53 am
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Deal Addict
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Aug 13, 2005
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Peterborough

How often should I change the spark plug and oil in my lawn mower?

I Have a Cheap MTD Lawn mower and I'm trying to start to cut grass for something to do. I know the lawn mower has not had an oil change in about 3 years So I will be doing that this week, but how often should I cahnge it and the Oil it runs fine now though.
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Sr. Member
Mar 17, 2010
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behind your left sho…
For my Honda "walk behind" push mower, I change its 4-stroke engine oil 1 x per year (every spring) - since condensation can form inside its engine chamber during its winter storage months. I use the exact same SAE number they recommend in their manual. Since lawn mowers tend to take a beating at my house, I use only use synthetic engine oil within it. And, run same engine oil for entire year. Works great for me.

You may want to do the same for your MTD Lawn mower as well. re: Yearly oil changes and only use symthetic - at same SAE number they recommend in your manual. Especially if you cut grass that forces the mover on its side for extended periods of time. Synthetics help reduce engine wear when lawn mower unit is on its side (re: cutting hills position) - so I've been told a few times. For its spark plug change interval, I might change the spark plug in my Honda's engine every 3-5 years. For this specific part, I'm more of a "if it works, no need to change it" attitude. Changing engine oil every year (every spring before 1st usage) is much more critical.

If you lost your lawn mowers manual, you can obtain another at http://www.mtdcanada.com/model-search.asp Note: Simply enter your unit's exact model or exact serial number. They will provide you the appropriate manual.

Hope this helps..

.
Sr. Member
Dec 5, 2007
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NB
I typically change both the oil and the spark plug once per year.
Both are cheap and easy insurance to keep your mower running in top condition all summer long.
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Jul 15, 2006
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I change the oil one per year and spark plugs every 2 yrs. When you pull the plugs inspect it to get a better idea of how often you should change the plugs. Sometimes re-gaping those plugs is all it needs if the plugs are in good shape. Oil is too important so I change that one a year.

All the best.
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Sep 1, 2005
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I change the oil at the end of every season. Don't want old oil sitting in there over the winter. Also I use up all of the gas before storage.

Spark plug. Haven't changed it since I bought the mower.

Mower is a self-propelled Lawn Boy. It starts on one pull.
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Dec 16, 2006
368 posts
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North of Toronto
gr8dlr wrote:
Jun 15th, 2010 4:06 pm
I change the oil at the end of every season. Don't want old oil sitting in there over the winter. Also I use up all of the gas before storage.

Spark plug. Haven't changed it since I bought the mower.
I'm of the same mind - why leave dirty/contaminated oil in the engine over the winter.
I change the oil every year after the last cutting (after running the gas out). Pull, clean and gap the spark plug. A bit of storage spray into the cylinder - couple of cranks - replace the plug and you'll be ready for next spring.
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Nov 9, 2003
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Grimsby
Never changed the oil or plug in 12 years on my old mower. This one is in it's second year, we'll see how it goes :)
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Mar 21, 2002
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Keep in mind that lawn mowers don't have oil filters so that there's nothing to stop metal filings and crud from circulating through the engine over and over again. That being said even if you never change the oil and completely neglect the mower, for the very limited number of hours it's used in a season it still would last many many years.

I guess though that I would look on it as you either do a good job looking after everything you own or you don't. I'm in the group that maintains everything well, and so I change the oil twice a year.
Sr. Member
Jun 13, 2010
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I haven't changed my oil for 3 years.... It came out the darkest of black I have ever seen! You probably will want to change it every season. I haven't changed my spark plug since new (8 year old lawnmower). It starts up on the first plug every season. I don't see why I should change the spark plug every season if it starts up on the first pull.
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Mar 21, 2002
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tommo4lyfe wrote:
Jun 15th, 2010 8:30 pm
I don't see why I should change the spark plug every season if it starts up on the first pull.
You're right, you don't need to change the plug if you're not having starting/running problems. That being said I do pull it out every spring, clean it up a bit and check the gap.
Deal Guru
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Dec 12, 2009
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Spark plug never, oil religiously once per year at the end of the season. With the small number of hours of operation, the spark plug does not wear at all. As for the oil, it get contaminated with raw gasoline and blowby easily. Mower engines are not quite as refined as car engines.
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Oct 12, 2001
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Oil & Air Filter Annually. Plug, when it runs bad I change it.
What the H E double hockey sticks have I done now?
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Aug 9, 2004
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woof wrote:
Jun 15th, 2010 7:31 pm
Keep in mind that lawn mowers don't have oil filters so that there's nothing to stop metal filings and crud from circulating through the engine over and over again. That being said even if you never change the oil and completely neglect the mower, for the very limited number of hours it's used in a season it still would last many many years.

I guess though that I would look on it as you either do a good job looking after everything you own or you don't. I'm in the group that maintains everything well, and so I change the oil twice a year.
Oh I'm sure theres a magnet somewhere in there to attract metallic filings.

But your point about maintenance still stands.

Oil and plug every year, clean air filter as needed, fuel stabilizer at end of season.
Always runs great.
Thanks for the memories, RFD.
Good-bye.
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