1st - Whatever plug came from the factory will be an AC Delco plug (AC Delco is GM's brand, they own it, why would they use another brand?). I do know for a fact AC Delco has re-badged NGK plugs before (seen it with my own eyes, AC Delco plugs with both AC and NGK markings). But I've never heard them using BOSCH. If AC Delco will re-badge a plug, that means it meets their specs and requirements OR that 3rd party vendor made a line JUST for Delco.

2nd - I've personally used BOSCH plugs and known others who have also done the same. THey are JUNK. Might be junk the moment you finish the job, might be junk 6 months later, bottom line, junk. In GM engines (at least 3100/3400/3800, they are known to have issues either immediately or shortly after). I know a guy that spent about 2 months trying to find the problem (he had a mis-fire before and after changing the plugs, turns out, he had a bad BOSCH plug out of box).

3rd - I've lately been using NGK Platinums. I can normally get them from RockAuto.com for $2-$3 a plug, they work GREAT! They are in mt '94 Grand Am, the wife's '04 Impala and my '02 Grand Am GT (all 3100 and 3400 engines).

4th - Some people may have good luck, some people may not follow a drive train and the parts that service it. BOSCH plugs I hear are great for the imports. But again, for the GMs, just personal experience talking the plugs are junk, the wires are great. This is NOT an attack on BOSCH (they have thousands of products, just this one is NOT ideal).

As for the engine temp, you do NOT want to do it when the engine is hot, you may injury yourself on things like the manifolds OR the expanded metal may pose issues removing the plugs and messing up the threads in the heads. Slightly warm or cold prefered. Also, i recommend a touch of anti-seize on each plug and a good dab of electric grease (most wire's come pre-greased, I've gotten to the point of adding a dab extra). It helps keep moisture out of or forming in the boot, makes future changes easier.

Best of luck and hope this helps answer some questions.

 

NGK Iridiums ... 03 SS 3.8L

 

personally, i run ac delco copper in every car i own. coppers have the least resistance than any other metal plugs are made of and burn better, thats not opinion thats just fact. and delcos are always a quality plug. yes, iridiums last longer than the coppers but the copper run better and when you look at the price its basically the same you just change the coppers more often

 

Dude use what ever plug you want. The whole rumor of dont use bosh plugs is crap cause if you know what your doing bosh plugs work just as well as any other and I can prove it. I just put a set of bosh plats in my 03 and changed the wires to bod and she runs like a champ. Use what you want. But the back plugs are kinda a bitch though

 

If put bosh plugs an wires on 2 old molars and one be big and I have bosh plugs and wires on 4 gm products 2 trucks 1 van and 1 car. Never had any issues with them

 

The BOSCH rumor is not a rumor for me, I have FIRST hand experience with more then one v6 GM and BOSCH plugs. BTW - I KNOW what I'm doing, this isn't my first rodeo.

I thought BOSCH would be a good name in plug, the parts stores promote them well. I personally had multiple first hand BAD experiences with BOSCH plugs not lasting more then 6 months before the car mis-fired. That made me swear off BOSCH plugs for myself. Then about a year or two later I know a guy who had a problem with them new out of box (changing plugs on his wife's Impala due to mis-firing, figured the plugs were due, it STILL misfired, he pulled all the BOSCH plugs out and I think went to AutoLite, no more issue). I've know others too with bad BOSCH experiences.

I know some people have had good BOSCH plug experiences. Say what you will, but for ME, I'm not going to spend the money on a product line I feel burned by when the SAME money gets me an OEM or better quality plug that will go the long haul (as it should). The guy wanted advice, he got our input, he can do as he wishes.

 

You are 100% correct, AC Delco is/are top quality product across the board, ... All I was doing was stating what I use, with a new set of Delco wires, of course.

 

In my 2001 Monte Pace Car I put Bosch in and had nothing but problems with the engine pining.
I took them out and put in AC Delcos and never had problems with the engine pining.
Yes, I admit, I put elcheapo spark plug wires in and now the engine is missing after 1 1/2 years but what is a poor guy to do when doing the best you can do with the money you have.
But, don't skimp on buying AC Delcos... and make sure the spark gap is right.

 

If people want to ruin their engine by it pinging then put another brand spark plug in, but, AC Delcos are the way to go with these engines.
Yes, I had problems with the engine pinging with Bosches.

 

i still am a believer in delco wires and coil pack. i also like there plugs but i also use the ngk plugs as well. i noticed the ngk platinums run very well for the 3500. i found that the dealer i go to for the pan drop and fill they only use the ngk for that puticular engine i ask why they said it seems to not have a issue for the engine. i am not complaning i perfer a plug that runs well for a engine. even better for it if a dealer sees a better performance out of the platinums vs stock delcos even though some delcos share the same part number.