How often do spark plugs need replacing? on 2006 Mitsubishi Endeavor

Why is it so expensive?

Mitsubishi recommends replacing the spark plugs every 30,000 miles. The reason the expense is so high on your vehicle is due to the labor cost. It takes over 2 hours to replace the spark plugs on your Endeavor.
1 more answer
try iridium plugs they are expensive but last 3 times as much