How Often Should You Change Spark Plugs? A Guide to Intervals

Spark Plug Change Intervals: All You Need to Know

Spark plugs are a vital part of your vehicle’s engine. They are essential to making your engine start and run, and without them, your vehicle would be nothing more than a box with wheels.

Like every other engine component, they wear out with use and time, and heavy usage makes them wear out at a faster rate. But how fast? And how often should you change your spark plugs in your vehicle?

In this post, we explain how long you can expect your plugs to last, starting with standard life expectancy per plug type before delving into all the variables that might impact that lifespan.

How Often Should You Change Spark Plugs?

The change intervals can vary greatly depending on the types of spark plugs being used, the type of vehicle, and a host of other factors as well.

With that being said, there are four main milestone change intervals.

Every 20,000 to 30,000 Miles

30,000 miles has been accepted for years as the most common replacement interval.

Even today, low-quality plugs or those made with a less durable material (such as copper) should be replaced every 20,000 to 30,000 miles.

Every 60,000 Miles

Most quality spark plugs need changing at around 60,000 miles, and this is currently the most widely accepted change interval for most modern plug types.

Every 80,000-100,000 Miles.

Many mechanics and manufacturers are beginning to set 80,000 miles as the new standard for the industry, but most mechanics still suggest changing them sooner.

Every 100,000 Miles or More

100,000-mile change intervals is pushing the envelope, but it is becoming possible with the best high-performance models on the market.

Even high-performance plugs are going to be worn by the time 100,000 miles come around, but not necessarily to the point where performance is dramatically affected.

What Factors Affect How Often You Should Replace the Spark Plugs?

There are many factors that affect whether you should change your plugs sooner than recommended, or whether you will be safe to wait some extra time.

What Type of Spark Plug Are You Using?

Spark plugs are made of different types of materials.

Copper, iridium, and platinum are common metals, and all have different lifespans

Copper is good for electrical current, but doesn’t last as long as both iridium and platinum. Iridium and platinum are more durable materials, but the electrical current doesn’t flow as freely through either metal.

How Do You Drive Your Vehicle?

Vehicles that are driven hard usually require new spark plugs more frequently.

Stop-and-go traffic, frequent towing, and spirited driving all contribute to a high wear rate.

Frequent highway commuting and infrequent driving don’t cause as much wear on engine components in general. 

Is There Any Oil Leaking onto Your Spark Plugs?

If you know your vehicle is leaking oil onto the plugs, you will need to change them more often.

As oil leaks onto the spark plugs, they will corrode faster, and carbon buildup will result from unburned fuel.

O-ring seal replacements will usually fix this issue, but not always.

How Old Is Your Vehicle?

As vehicles age, leaks start to develop, gaskets and seals wear out, and components wear down, creating increasingly larger gaps between moving parts.

Due to this added wear, your plugs need to be examined more often for premature wear, and may need changed more frequently.

Signs That Your Spark Plugs Need Replaced

There are several warning signs that you have a bad spark plug and an immediate change is needed. If you don’t/haven’t experienced any of these symptoms with your car as of late, then you probably have good spark plugs.

Your Engine Is Idling Roughly

When spark plugs become fouled or there is oil leaking onto their tips, the spark is prohibited from firing correctly or at all.

This can cause the engine to hesitate, which will make it run at a rough idle.

Your Engine Stalls

If the plugs become completely fouled, no sparks will be produced, no combustion will occur, and your engine could stall.

Trouble Starting Your Vehicle

Just like the lack of spark in the bad spark plugs can cause an engine to stall, it can also prevent it from starting again.

This is especially common when there is oil leaking onto the tips.

Oil doesn’t have a chance to burn off in the combustion chamber when the engine is on. Droplets of oil can prevent any sparks from occurring at all.

Your Vehicle Experiences Slow or Jerky Acceleration

If your spark plugs haven’t been changed in a while, your vehicle could experience decreased performance due to the decreased ability to produce sparks.

A car that has trouble accelerating, or your car jerks when accelerating, is a prime example of that.

Your Check Engine Light Is On

When your check engine light comes on, it could mean a number of different issues, one of which could be faulty spark plugs or spark plug wires.

(Remember that a check engine light flashing could signal serious trouble).

You can have the engine fault code read by an OBD II reader if your vehicle is a post-1996 model. 

Poor Fuel Economy

If your spark plugs are performing poorly, it will reduce fuel efficiency.

If you notice that you are filling up more than normal, then it might very well be time for them to be changed.

Your Engine Has a Misfire

A misfire is one of the most serious issues your engine could encounter, and it could be caused by the lack of sparks being produced by a misfiring spark plug.

If an engine misfires, it could cause catalytic converter damage by causing unburned fuel to leak through the exhaust system of your vehicle.

This problem could be caused by more than just misfiring spark plugs, but examining them to see if they need replaced is a good place to start.

Are There Any Other Tips I Should Know About Changing Spark Plugs?

Your owner’s manual will let you know the exact timeframe in which you should change your spark plugs. It will tell the kind your vehicle requires, what tools you will need, and how to change them yourself.

Also, keep in mind that you know your vehicle better than anybody else. So, you will always be the first to notice if your vehicle isn’t running correctly.

It is also important that you don’t ignore it when this happens. Spark plug failure could cause severe engine damage, potentially resulting in thousands of dollars costly repairs.

Last but not least, just because a certain spark plug, mechanic, or even your vehicle manufacturer says you should change the plugs at a certain mileage doesn’t mean you can’t change them sooner if necessary.

If you know that you run your vehicle hard or that your vehicle isn’t performing as well as it usually does, it’s likely time to switch out your spark plugs!

Wrapping It Up

Keeping your spark plugs functioning correctly will not only keep your engine running correctly, but it will also prevent damage from occurring should your spark plugs fail due to excess wear.

Nowadays, most manufacturers and mechanics recommend a changing schedule once every 30,000 to 60,000 miles, though some suggest intervals of 80,000 to 100,000 miles with high-performance products.

Being informed, regular inspection and maintenance, and knowing when to change your plugs will be one of the best and easiest things you can do to keep your vehicle running as it should.