But what about the spark plugs themselves, though? How often do they need to be replaced now?

Manufacturers tout an 80k-100k mile service interval on spark plugs now, thanks in part to improvements in plug design and materials. That might be stretching it, however. Remember that if you have a 100,000-mile spark plug, its electrode is worn down 4/5 of the way at 80,000 miles. A worn electrode means a wider spark plug gap, which can mean a loss of power and fuel economy.

Worse, though, spark plugs that have been in the engine’s cylinder head for years and tens of thousands of miles have a tendency for their threads to seize. A seized spark plug can be pretty difficult to extract from the head and can mean a hefty repair bill before it’s all said and done.

If your vehicle was originally equipped with a specific type of spark plug, it’s a smart idea to keep that design of plug when you replace them. It’s also a good idea to check a few other things under the hood when it’s time to replace the plugs, including

--Air filter

--Cabin air filter

--Belts and hoses

--Charging system

--Starter

--O2 sensor

--All vacuum lines and junctions

Today’s cars may be a lot less maintenance-intensive, but that doesn’t mean “maintenance free.” Remember that a well-maintained car is a reliable and strong-running car…and don’t put off maintenance like spark plugs just because it doesn’t need to be done very often!