Originally Posted by captainofiron

6 months really? then you have no valid experience, unless you travel 50-100K in 6 months.

judging an automotive part by how it performs in 6 months is by no means a grueling test.

I had AC delco platinums in my Trans Am for 4 years and it was fine, I bought into the hype of the bosch platinums (funny enough in college when I was a parts manager at a pepboys) and put them in, my gas mileage dropped and the throttle response, needless to say after about 10K they were out of there, I put the delcos back in, and everything went right back to it had been before.

and no it just wasnt bias, I keep a log book with mileage between fill-ups

dont believe everything they teach you in those product knowledge courses at the counter jockey classes

Originally Posted by tjwalker

From 37 years of wrenching and working on just about every year of XJ, my spark plug recommendation is;

84-99: Champion coppers

00-01: NGK (the 00-01 has a distributorless coil-pack ignition which makes the NGK a slightly better choice)

I have had and seen mysterious "misfires" with Bosch spark plugs on the Jeep 4.0 engine, and will not use them nor recommend them. Those misfires went away when the Bosch plugs were replaced..

To be fair, not all 4.0 engines have trouble with them, but I've seen enough not to want to take the chance, when you have such an established track record with the above.

Originally Posted by tjwalker

From 37 years of wrenching and working on just about every year of XJ, my spark plug recommendation is;

84-99: Champion coppers

00-01: NGK (the 00-01 has a distributorless coil-pack ignition which makes the NGK a slightly better choice)

I have had and seen mysterious "misfires" with Bosch spark plugs on the Jeep 4.0 engine, and will not use them nor recommend them. Those misfires went away when the Bosch plugs were replaced..

To be fair, not all 4.0 engines have trouble with them, but I've seen enough not to want to take the chance, when you have such an established track record with the above.

Originally Posted by Dre

Then it is safe to say under vehicle maintenance, you are damaging your engine. From what I learned in school and a dealership, to maximize the life of a vehicle, 3000 or 3 months on plugs... Pre-iridiums. And I have had plugs in cars for a year. Fuel economy is more important. And I used to rebuild engines for fun. Plugs that long, will cause major engine problems. Check the service manual. It stated it in the 89 Jeep I had. But I guess my experience is no match for your judgement.

Posted by: Dre

Originally Posted by 84zmyfavorite

Ive taken Bosch Platinum 2s and 4s with exploded ceramic insulators as well. I would really recommend plain Jane Autolite copper core or factory Champion copper core. I have 6 Cherokees in my name now(two 84z, 0ne 87, a 96, 99, and my beloved 01), and they all have Autolite copper core spark plugs. Not one problem with any of these current Jeeps or past Jeeps fired by Autolites.

Originally Posted by captainofiron

lol, it seems like everyone is an expert on a forum.

I use to rebuild engines while I was waiting for my pop tarts to cook in the toaster

Originally Posted by BowtieGuy3

I've just always seemed to notice if it came from Chrysler, it will usually always run good with Champions.

Originally Posted by captainofiron

Thats impossible, according to Dre those plugs are made from German unobtainium /sarcasm

Originally Posted by Dre

Not a big fan of champion. Well, at least more than 10 years ago. I go by if my gas mileage is good or bad.

Posted by: Dre

Originally Posted by Uhrinator

So which ones would you get for the best mileage?

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