Things to Know About Spark Plugs - Service Information at Hanson Subaru in Olympia, WA

Spark plugs may be small, but the role they play in making sure your Subaru runs is huge. Despite their importance, they're a relatively low-maintenance part. This means that many people don't think about them often, and may not even know what they do. At Hanson Subaru, we want to help you learn more about your vehicle. That's why we've put together this page with information on those small but important spark plugs.

Spark plugs are screwed directly into the cylinder heads of your vehicle 

4. How Spark Plugs Function

Unless you're driving an all-electric vehicle, your car uses an internal combustion engine. Gasoline engines are the most common for passenger cars, and all new Subaru models currently for sale in the United States use this type of engine. To create combustion in a gas engine, a spark is necessary. A mixture of fuel and air is injected into the combustion cylinders, and then compressed by the piston. A spark ignites this gas, which propels the piston down the cylinder. The spark plug is what provides the spark. It's a piece that's screwed into the combustion chamber. A current travels along the inside of the spark plug; when it reaches the end, the current will jump from one electrode to another across a small gap, creating the spark.

Current jumping from one electrode to another causes the spark 

3. Spark Plugs Come in Different Materials

Spark plugs have both metal and an insulating material, and the most common metal for the core of a spark plug is copper. But the electrodes on the end of the plug are made of different metals, with three metals being the most popular. Despite the name, spark plugs referred to as "copper" spark plugs actually have a nickel-alloy coating on the electrodes. Then, there are two varieties of platinum spark plugs. Single-platinum spark plugs have a platinum disc on the electrode that's attached to the core, while double-platinum plugs have a platinum disc on both. At the top of the line, you have spark plugs coated with iridium. These last longer than the other varieties, but they are more expensive.

2. Spark Plugs Will Wear Out

Though spark plugs don't need to be changed nearly as often as some other components in your vehicle, they will wear out eventually. The gap between the two electrodes will become less precise, making it harder for the spark to jump. Your owner's manual will tell you how often you should change the spark plugs in your engine. However, there are a few things that can cause spark plugs to go bad early. If oil is being burned in the cylinders of your car, the plug's lifespan can be decreased.

Spark plugs will eventually need to be replaced 

1. Bad Spark Plug Symptoms

If your spark plugs aren't working as well as they should be, you might notice that starting your vehicle is difficult. After all, spark is one of the key things that makes your engine work, along with fuel, air, and compression. This also means that, if you do get your engine going, acceleration may become difficult and idling could be rough. If you're noticing symptoms like this, it's best to have your spark plugs inspected immediately.

Hanson Subaru

2300 Carriage Loop SW
Directions Olympia, WA 98502

  • Call or Text Sales: 360-943-2120
  • Service: 360-943-2121
  • Parts: 360-943-8531


  • Monday 07:30am - 06:00pm
  • Tuesday 07:30am - 06:00pm
  • Wednesday 07:30am - 06:00pm
  • Thursday 07:30am - 06:00pm
  • Friday 07:30am - 06:00pm
  • Saturday 07:30am - 06:00pm
  • Sunday Closed