How often to change spark plugs? When (and how) to change?

How often to change spark plugs? When (and how) to change?

How often to change spark plugs? When (and how) to change?

Should you change your lawn mower's spark plugs every 25 hours? 

NO! This is a common misconception, below is what you need to know.


With so many factors to maintain your lawnmower properly, it can quickly become overwhelming. 

And one of the many questions you may face while maintaining your lawnmower is how often should you change your spark plugs?

This is crazy, but we found out that there is a lot of misinformation on how often spark plugs need to be replaced.

So naturally, we did some digging, and we also reached out to some lawn care pros to ask them what they think.

Below you will find EVERYTHING you need to know about how often you should be replacing your mower's spark plugs.

Image of a Spark plug for a lawn mower

In a nutshell: How often should lawn mower spark plugs be replaced?

In short: As a rule of thumb, the average homeowner should be ok if they change their spark plugs out once a year. 

The same is true of all your lawn care equipment in general, including commercial weedeaters.


Here’s the deal, most websites appear to recommend that you should replace your spark plugs every 25 to 30 hours of operation


Get this, the lawn care professionals we spoke with had something entirely different to say. 

With well over 50% suggesting that they only replace their spark plugs ONLY once a year

Which would suggest that spark plugs operate efficiently for much longer than other mainstream sources suggest. 

But we will cover that more in a minute. 

Lawn care professioanls reported to us that they change their spark plugs annually.

How Long Should Spark Plugs Last in a Lawn Mower?

Spark plugs play a big part in keeping your lawn mower running well. But how long do they last? Usually, spark plugs in lawn mowers can last a pretty long time, often more than what most people think.

For someone who uses their lawn mower just for their yard, a spark plug can keep working for many years. This is because the mower is used only a few hours each week during the mowing season. In terms of how many hours they last, it could be anywhere from 100 to over 500 hours of use. Thanks to better spark plug designs, they work well for longer.

This can change depending on your mower's model, the kind of spark plug it uses, and where you use the mower. Mowing in dusty or dirty places can make the spark plug get dirty faster, which might mean it won't last as long.

Why do I need to change the spark plugs in my lawnmower?

Think about it, as the ignition source for your lawn mower's fuel. Your spark plugs create a spark 1000’s times during the process of cutting your lawn. 

And during the process of igniting fuel over and over and over. Your spark plugs can get deposits built upon them and they will eventually become too corroded to ignite fuel efficiently. 

Other potential reasons you are spark plugs may need to be replaced include:

  • Rust,
  • Cracked ceramic,
  • And improper gapping.

Whatever the case, your spark plugs should be changed on a regular basis to prevent efficient lawn mower operation. This is simply a part of proper lawn care.

But how often should you change your spark plugs? 

Let’s look a bit deeper.

What is the industry standard? 

Here's the deal, for one reason or another, most sites recommend changing your lawnmower's spark plug every 25-30 hours.

While I am not sure why this misconception has taken over, it may be due to this article by Briggs and Stratton.

The article states that you should "check and/or replace" your spark plug every 25 hours. 

Somehow the 'check and/or'' part got overlooked in other articles who mistake that "the life of a spark plug is 25 hours". -Source

However, in all fairness, the Google Search result is a bit misleading, and shows why a deeper investigation into search results is a must!

Google search results for how often should you replace your lawwn mowers spark plugs

However, one has to wonder…

Is Briggs and Stranton intentionally misleading consumers to make more spark plug sales? 🤔 

Look in my experience, spark plugs last 100's of hours… easily. Changing your spark plugs out every 25 hours is way too frequent. 

However, it's difficult to come up with a better number on our own. So we reached out to other lawn care pros to see what they recommend. 

Here is what they had to say...

How often do lawn care professionals change spark plugs in their lawn care equipment

What do the lawn care pros say about replacing a spark plug on lawn care equipment?

Across the board, the resounding response from lawn care providers was that they changed their spark plugs annually. With 64% reporting to us that they only changed their spark plugs once a year.  

This number suggests that spark plugs last MUCH longer than 25 hours. 

Think about it we are talking about lawn care professionals. So if they run their mower for a minimum of 20 hours a week for 39 weeks of the year for example. That means spark plugs easily last over 780 hours before needing to be replaced!!!

What did the rest of the lawn care professionals say about changing their spark plugs? 

Well, the second most popular response we received was 30% of lawn care pros stating they NEVER change their spark plugs.

Finally, 3% of lawn care providers said they changed their spark plugs after the 'recommended' 25-30 hours of use, and another 3% reported to us that they swap spark plugs out on a monthly basis.

Broken spark plug in lawn mower

Remove Spark Plugs Regularly to Prevent Seizing

Look, whether your spark plug ignites the fuel or not is one thing. But one huge issue that can occur when your spark plugs are not maintained is seizing

Here's the deal, a bad spark plug isn't a huge problem, but a seized spark plug can be a major headache. And could potentially cause other problems down the road. 

Spark plugs can seize inside the engine block if they are left in too long, or improperly installed. 

So, even if your spark plugs are still good, you want to be sure to remove them annually and add an anti-seize agent at the very least.

Spark plug in small engine

When to Change Your Lawn Mower's Spark Plugs

Knowing when to change your lawn mower's spark plugs is important. How often you need to do this depends on how much you use your mower and what kind of mower you have.

A good rule for most people is to change the spark plug once every year. This fits well with the usual care schedule for most lawn mowers and helps keep your mower in good shape.

If you use your mower a lot, like for a lawn care business, you might need to change the spark plugs more often. In these cases, changing the spark plugs every six months or so can be a good idea. This is especially true if you use your mower a lot each day, like many lawn care professionals do.

But these are just general tips. The best thing to do is to check your spark plugs regularly for any signs of wear or damage. Look for things like rust, cracks, or a lot of dirt. Also, notice how your mower is running. If it starts having problems like being hard to start, not running smoothly, or not working as well as it used to, it might be time for new spark plugs, even if you haven't changed them in a while.

Spark Plug Maintenance at the End of the Day

Don't change your lawn mower spark plugs every 25 hours! That's a myth. Most homeowners only need to change them once a year. Even lawn care pros often only replace them annually or never.

Here's the deal:

  • Spark plugs last longer than you think. They can handle 100-500+ hours, depending on your mower and use.
  • Changing them too often is a waste of money.
  • Ignoring them completely can cause problems, like seizing, but annual checks and anti-seize lubricant help.
  • Use your judgment: If your mower isn't running smoothly, check the plugs.

Bonus tip: Lawn care pros might need to change them more often (monthly) due to heavy use.

Simply put, if you are a homeowner you probably can't go wrong changing out your lawnmowers spark plugs annually. 

Most homeowners use their lawnmowers well over 30 hours annually. So it simply makes sense to swap out your spark plugs on an annual basis. 

On the other hand, if you are a lawn care pro, only changing your spark plugs once a year may not be enough. And you do risk sacrificing your lawnmower's performance by not changing your spark plugs frequently enough. 

While it's a fair assumption that changing out your spark plugs weekly is a bit overkill. You may want to consider changing your spark plugs on a monthly basis if you are a lawn care vendor

But the reality is, your mowers spark plug goes mad, it's not a difficult fix. At least if you happen to carry spares on hand. 

Want more to read? Check out this article on how to winterize your lawn care equipment.

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