Most drivers know that you should change your spark plugs routinely to keep your car's engine running smoothly. However, when it comes to gapping spark plugs, many people may find themselves confused.

We may receive a commission on purchases made from links. When it comes to engine care 101, a spark plug replacement — also referred to as a tune-up — is an essential task. Spark plugs, as the name ...

For hot rodders, spark plugs are often nothing more than inspection tools that reveal whether an engine is running too rich, too lean, or just right. Street guys look for a nice tannish-brown tint on ...