All of the above posts have some valuable and healthy skepticism. I have posted before on spark plugs and my position is that if there is an advantage in horsepower gain, gas milage increase, or longevity, the automobile manufacturers would all be jumping on the new technology. If the new technology was patented, they would buy the patents.

I worked for Champion Spark Plug Co. for 25 years and between my father, grandfather and me, we had a cumulative 92 years there. I also have managed a Shell station and advised my customers to put in the same original plugs that come out. The only time you need to change heat range is if you are driving the car hard or racing when you would need a colder plug, or if you are driving in the city and your plugs are fouling, you need a hotter plug. This is less true today as in the past. With a copper core you can use a thinner longer profile to get the advantage of a hotter plug and still be able to dissipate the heat out of the plug mimicking a cold plug. In other words you have a greater heat "range" built in to modern spark plugs today.

The one element of truth in the ad is that a spark jumps most efficiently from a sharp edge. That's why in the past with conventional ingition systems you needed to replace pugs after about 10,000 miles, the edges got rounded. Leaded gas also fouled plugs after about 10,000 miles. With todays electronic ignitions, the computer compensates as the plug wears and looses it's sharp edges.

It always amazes me that there is a definite " perceived performance" boost that occurs when replacing spark plugs. If I told you I put a new type of plug in your car and told you it will boost your horsepower by 10 percent, most would say they "feel" the difference even if I didn't change the plugs.

Our plugs in the Crossfire were designed to go for 100,000 miles. It certainly won't hurt to replace the plugs but in most cases it's not needed.