Quote Originally Posted by brandonl2000 View Post
On a 1999 Pontiac Grand Prix GT 3.8L, I am wanting to do a basic tune up when I get it. I would like to put new plugs and wires and do the oil and fluids etc. I was reading the "Safely Modding" thread and it was talking about putting cooler plugs in there. It has a stock engine. I intend to put a short ram intake on it a little later on. Which plugs do I need; Autolite 605 or 606? What is 1 heat range cooler going to do and what could it hurt?
Also I would like to replace the thermostat, as keeping the engine cooler would be more efficient, correct? So which is better; the 160 or 180? I don't want to mess up and end up hurting my performance.
And what is step 8 where you do the Transmission Pan Drop/New GM Transmission Filter? in detail... and is it even necessary?

Thanks!
Brandon,
I work as the technical manager at Autolite. As long as you have not done anything to raise the boost or compression in your car, you should not use a colder spark plug. there is simply no benefit to doing so at all. What may happen is a fouled spark plug, a failed cold start or partially fouled plugs. The reason you would need to go to a colder plug can be found by watching the videos posted at www.autolitechallenge.com/pro. The 5th video in the series explains what spark plug heat range is all about, when and if you would need to change heat ranges. You can also get a Autolite branded Carhart jacket for watching all 6 video's. There is one video about the DIS ignition on your car as well.
You should also stay away from using a copper core spark plug unless you really enjoy changing spark plugs. Your DIS ignition fires one half the spark plugs in the opposite direction, meaning the spark actually jumps from the side wire to the center wire. using any copper plug in a DIS ignition vehicle is a mistake that will cause rapid degradation in the sidewire and misfires in as little as 16k miles. Use the Autolite XP606 Iridium fine wire plug. Yes, they cost 7 bucks a piece. They are worth it. They take less ignition voltage to fire and have a 25% larger flame kernal than the stock plug. The also have a platinum button on the side wire to prevent gap erosion. They have a 100k life span as well. If I can answer any other questions for you, please feel free to contact me at Jay.Buckley@Honeywell.com