This has been covered before, but I thought it worthwhile to share my experience...

I bought this truck, and the previous owner said he had just replaced the plugs 10k ago, among other things (re oiling the K&N, etc). He said not to bother doing em as he had bought "the most expensive plugs", which turned out to be the bosch 4 prong plats.

You would not believe the difficulties I was having with this truck. Poor gas mileage, hard starts, and finally no start. And why? Because I was running on MAX 5 cylinders, more likely 4.

When I finally pulled the plugs (after replacing my spider and nut kit to no avail) I couldn't believe the condition they were in. All of the plugs were covered in black sooty crap, and two of them had major *chunks* of carbon between the electrode and the prongs. These chunks had the thickness of a CD and were as wide around as a pea.

So when people here recommend you use nothing but AC delco rapid fires or plats, listen. Now that I have the rapid fires in my truck its running great.

Another good reason not to run Bosch Plugs............

10-4 on that.
Factory OEM only hurts one time.
MT-2500

Not that I would run anything but Ac Delco plugs but what is with the Bosch plugs running like shit in our engines? I used Bosch plugs on a jeep Cherokee I owned with just under 200,000 miles on it and thing purred like a kitten and was still powerful. I really liked that vehicles except for the god awful colors of the plaid interior!

The jist of what I've gotten from other discussions is that we drive "expertly and finely tuned machines" that run like crap when you stick a plug in that's gapped differently / runs at a different temp than OEM.

This is yet another story to be filed in the Bosch Garbage can...

Yip, they just don't have any lifespan.