Spark Plug Heat Range Conversion Chart
 

For those interested in getting the correct heat range plug for your car, here is a handy dandy chart that might give some insight if you don't go with NGK plugs. Correct me if I am wrong, but I think the OEM heat range for our cars is a "6" if you are using NGK plugs.

Heat Range Conversion Chart

I was concerned when I replaced my plugs the other day because I just picked up the Bosch plugs that AutoZone said would work in my car (an SRT). After seeing some other members questioning the heat ranges, I thought I'd see if I messed up.

The plugs that AutoZone gave me were Bosch 9603 with a heat range of 7, which compares to an NGK heat range of 6 so I think I am OK. Kind of odd, but when I go to the AutoZone web site and put in my specific car and engine, it states I should use the Bosch 9600, which is a heat range of 8. It recomends the same Bosch plug for the N/A, so I am assuming that both engines (if stock) use the same plugs.

RL

Re: Spark Plug Heat Range Conversion Chart
 

There are different plugs for the srt6 vs NA. I assume you stuck with the 9603...any issues?

Re: Spark Plug Heat Range Conversion Chart
 

Yep - I used the 9603 plugs and so far have had no issues. The car runs smooth and my mileage has gone from around 18 to about 21 with a mix of city and highway driving. One of these days I will get through a tank of gas without sticking my foot in it so I can see how good of an MPG it will actually give me ... but that's not real high on the list of things to do ;)