As a Do It Yourselfer, I never rely on mechanics to change my car’s spark plugs because I rather save the extra $50 in labor. It’s not hard and for most import cars, it’s easy as wrenching out the spark plugs. For domestic cars, you might have to unscrew some car parts but still, it’s very do-able and once you get the hang of it, you will start saving money on car maintenance for the future.
For reference, check out this video that shows you how to change spark plugs:
video://www.youtube.com/watch?v=dnwXFDwZ8PI
If you have trouble finding out where your spark plugs are, simply google it, you should be able to get enough information to locate your spark plugs.
Also see About.com and eHow.com if it’s your first time replacing those old spark plugs.
