*I have a 4.0L STR6 in a 99' JGC Laredo* I have searched and found a useful thread on sparkplug recommendations but through many conflicting viewpoints I would like to verify that opinions haven't changed in 2 years...so I heard that Champion "Truck Plugs" are "best" for the Jeep. I also saw these Iridium ones here Is the $4 price hike worth it or should I just go with the truck plugs? I can find the Champion truck spark plugs in any autoparts store too correct? Also, should I change the coil and boot from the coil rail each time I change spark plugs too? Or can I just add spark plugs and slap the rail back on?

Thanks!

Stick with the Champion or Champion truck plugs, no need to change the coils unless they're bad.

I actually meanted boot and SPRING, someone corrected me on this. Should I change the spring that makes contact with the plug?

no its come with new wires

*I have a 4.0L STR6 in a 99' JGC Laredo*...so I heard that Champion "Truck Plugs" are "best" for the Jeep. I also saw these Iridium ones here Is the $4 price hike worth it or should I just go with the truck plugs?
Thanks!

I tried some platinum plugs for a while, but they seemed to almost feel like they missed once in a while...put in the Truck Plugs and haven't had a trouble since.

So I'd stick with those.

Does not have plugwires,has coil on plug ignition system and avoid Bosch plugs.Bosch plugs are the worst plugs for Chrysler products including Fords and GMs.I see them,they get removed and pitched in the garbage can.I agree,stick with the Champion plugs.Avoid the E3 plugs,I have heard they are also a piece of junk and did cause a missfire in a Chrysler product.

my 2004 4.0l came with ngk plugs from the factory, i used champion on the last tuneup and have not had a problem yet

I have a 96 GC Laredo 4.0 and the sticker under the hood calls for RC12LYC Plugs well I put some new Bosch Double platnum non gap plugs in and when you are in idle it will sometimes stall, hesitation when pulling out into traffic and it mimics a lot of problems for which you could spend a lot of money on. Today I was changing my oil and I saw that sticker and decided what the hell, I went to Napa and got the original OEM Plugs at $1.59 a piece. When i pulled the expensive plugs out they had black soot on them and the Haines manual said that that could cause the engine to hesitate and stall. I put the new ones in and started it up and it sounds brand new. I disconnected the negative terminal and reset the computer. Now we will see if things get better. More expensive doesn't always mean better. Max

Yep, the 4.0 loves the inexpensive Champions, and also, like beat88ls said, in 2004 some came with NGK plugs. (as did mine).

I've had absolutely no problems with either plug; just be sure to change them every 30k miles....each time I change mine I'm surprised how smooth the engine is and I also see a rise in mpg.