"I put these in my 06 Ram 1500 4.7L and watched my mileage increase for the first 5k and then drop to 12mpg highway for the next 10k. Thought it was just a dirty engine until I got fed up enough to change the plugs out. I switched to NGK V power and back to a consistent 18mpg on the highway. That was a year ago. Don't waste your money on these. They DONT WORK."
How often do you shop at JC Whitney.com? Once a Year
Cons: Cracked and had to keep replacing them over and over.
"I put these in my 02 PT Cruiser. Granted I am used to my car going through spark plugs quickly but these were ridiculous. I would get no more than 5k out of them and I would have to replace them again. They were always cracked and well worn from my engine after such a short time. They lasted a bit better in my brothers 04 neon but they certainly didn't come anywhere close to the 100,000 mile claim and didn't even last as long as the 30,000 service interval on either car. If you are prepared to work with the warranty and change them often they do help power and fuel economy but they do not last."
How often do you shop at JC Whitney.com? Multiple Times a Year
"I bought a set of 8 of these spark plugs for my 2000 GMC Sierra. 1 of them was deffective as soon as I installed them. Had to wait for JC Whitney to send me another one. 2 more went bad in under 10,000 miles. These are JUNK ! Don't waste your money or time."
"Guaranteed for 100,000 miles right? Yea ok, I got 58 miles out of mine before they fried both my ignition coils and the plugs thought I was going to be saving money on gas instead I ended up paying $150 in parts to fix my car. These plugs are garbage, I would not recommend them to anyone. STAY AWAY!!!"