: ACDelco Iridium spark plugs



M.A.C
08-02-10, 11:31 AM
I want to change my spark plugs and I'm thinking of buying ACDelco Iridium plugs at about $7 each. OEM platinum plugs are a bit cheaper, but I have hear good things about iridium.

I also was considering the Pulstar plugs but I they are about $12 a plug and there are claims that the fire too hot and can burn a hole in pistons. So, I figured I would stick with ACDelco but get iridium instead of platinum.

CadillacSTS42005
08-02-10, 11:34 AM
Please dont put anything in but oem, you will be doing it again if you dont.
If the N* needed iridium they would be installed from the factory, still with AC delco plats only.

C&C
08-02-10, 02:35 PM
The OEM are good for 100,000 miles. I see your vehicle has 173,000 (and assuming that they have been changed at least once), I would stick to the OEM platinums. I have iridiums on my motorcycles engine (FJR-1300) but that is to extend my mileage interval from the factory recommended 8,000 miles to 16,000; your situation doesn't seem to require the higher dollar plugs. JMO

M.A.C
08-09-10, 03:04 PM
I went to PepBoys and bought 8 Champion Iridium spark plugs for $5.95 each. Also, there is a rebate until 8/31 of $2.50 a plug = $3.95 a plug after rebate. I'll install them and see what happens. I'll also keep my original plugs just in case.

CadillacSTS42005
08-09-10, 04:00 PM
Youll be doing it again.
Sorry Im just warning you.

M.A.C
08-09-10, 04:02 PM
Youll be doing it again.
Sorry Im just warning you.

Have you tried iridium plugs or is your view based on what you've heard?

CadillacSTS42005
08-09-10, 04:20 PM
I have plats in my STS and irid in my SS Camaro, I use whats reccomended always.
I have installed different plugs on N*s at work as its what the customer wanted, 9/10 times theyd be back in a few thousand miles with a low end misfire, guess what, it was using non delco plugs.

M.A.C
08-09-10, 05:10 PM
I have plats in my STS and irid in my SS Camaro, I use whats reccomended always.
I have installed different plugs on N*s at work as its what the customer wanted, 9/10 times theyd be back in a few thousand miles with a low end misfire, guess what, it was using non delco plugs.
I have heard about this. But the plugs are guaranteed by Champion to work. I'm saving the receipt in case I need to bring them back and exchange them for platinum.

CadillacSTS42005
08-09-10, 06:00 PM
Yea and the fuel saver magnets and tornado are guaranteed too...

porkfarm
08-09-10, 06:30 PM
I put NGK irads in at 55K. Not much of a diff from the stocks, but not a problem at all. In fact slightly better cold start. I was trying to smooth out the motor and thought I would try plugs. Plus I could see if one was bad or having issues. If I would have done the intake bolts, I might not have changed them. I would not use champs thou. Do a search on N* & plugs and read up.

CadillacSTS42005
08-09-10, 09:39 PM
AC Delco, NGK and Denso have all been OEM on N* at times.

EChas3
08-09-10, 10:05 PM
AC Delco, NGK and Denso have all been OEM on N* at times.

I'd expect in each case, they were manufactured to the GM Spec, not afternarket. I'm going OEM when I need 'em.

M.A.C
08-09-10, 10:33 PM
I put NGK irads in at 55K. Not much of a diff from the stocks, but not a problem at all. In fact slightly better cold start. I was trying to smooth out the motor and thought I would try plugs. Plus I could see if one was bad or having issues. If I would have done the intake bolts, I might not have changed them. I would not use champs thou. Do a search on N* & plugs and read up.

I thought about whether I should use Champion due to having a bad reputation over the years. The last time Champion was respectable from what I remember is back in the 70s. But I figure I'll give them a try and who knows maybe Champion is not bad after all. Then again, a few people in another Cadillac forum mentioned having problems with ACDelco platinum plugs, particularly the platinum "pucks" either falling off or looking like they are not on center. I know people like to stick with OEM but sometimes OEM can experience quality issues too. I would be pretty upset if I bought new ACDelco platinum only to have to replace them. At least with Champion, I know what I might find myself up against.

dkozloski
08-10-10, 03:13 AM
FWIW, the AC in ACDelco stands for Albert Champion.

Greg00coupe
08-10-10, 12:34 PM
What is your goal? Are you tying for better performance, gas mileage or what? My Corvette friends have gone with these plugs and seemed to be happy. But I'm not sure what that means?!?!? Hard for me to believe you drop in any plugs and can feel a noticeable performance difference.......... yea you might but that is due to new plugs vrs. old. For and STS driven on the street I'd do OEM. The older I get I lean more to OEM. Why make life any more complicated???

M.A.C
08-10-10, 02:26 PM
What is your goal? Are you tying for better performance, gas mileage or what? My Corvette friends have gone with these plugs and seemed to be happy. But I'm not sure what that means?!?!? Hard for me to believe you drop in any plugs and can feel a noticeable performance difference.......... yea you might but that is due to new plugs vrs. old. For and STS driven on the street I'd do OEM. The older I get I lean more to OEM. Why make life any more complicated???
I'm not looking for anything special with iridium plugs. There are claims about getting better mileage, but I'm more curious than anything. If they work and last 100K in better shape over their lifetime than platinum, I'll be happy.

M.A.C
08-15-10, 01:34 AM
I installed the iridium plugs today and so far so good. Getting at the passenger side rear plug was a pain because the harness is in the way. The left side was easy.

next2pool
08-17-10, 02:54 PM
In all my years of replacing plugs, the only time I've ever remotely noticed a change was on my old lawnmower!

cosmictrucker
09-06-10, 07:15 PM
AC Delco, NGK and Denso have all been OEM on N* at times.

I finally got around to changing the plugs in my 02 DeVille with 102k miles. I ended up buying a set of Denso double plats. I was a little surprised to see the original plugs were also Denso. I've owned this car since 29k miles, so I knew these had to be original.

(what was GM thinking with mounting that Air valve on the rear valve cover?)

M.A.C
11-24-10, 10:56 AM
UPDATE: It's been over 3 months and the Champion Iridium plugs are working fine.

KRSTS
11-24-10, 12:29 PM
Let us know after 3 years and 100K miles:histeric:

johnny kannapo
11-24-10, 01:30 PM
I don't see the problem, the Iridium Plugs are easier on the coils.

Deville4Jesus
08-25-13, 08:08 PM
Just installed these (9404) on my 89 Deville. Not sure how many miles were on the plugs but they were pretty toasted. Gas mileage wasn't bad but I felt it was time since the car has 102K and I've only had the car since around 80K.

Seem to be working well so far, I'm curious if the mileage will change at all.

EChas3
08-26-13, 11:00 PM
Members report the STS Northstar quite fussy about plugs. I think I'll just stick with the original when the time comes. (Iridium is tempting, tho.)

mjcaddy
08-26-13, 11:18 PM
I finally got around to changing the plugs in my 02 DeVille with 102k miles. I ended up buying a set of Denso double plats. I was a little surprised to see the original plugs were also Denso. I've owned this car since 29k miles, so I knew these had to be original.

(what was GM thinking with mounting that Air valve on the rear valve cover?)


hahaha, been there, done that (twice).

back to the subject, the only thing that I've heard about using non-oem plugs that the mpg reading in your driver information will be wrong.

EChas3
08-27-13, 12:59 AM
I don't recall a member post that result here.

wake
08-27-13, 01:26 AM
Please dont put anything in but oem, you will be doing it again if you dont.
If the N* needed iridium they would be installed from the factory, still with AC delco plats only.

Aren't the OEM plugs Iridium now?

Anyway, I've used the Bosch +4 platinum and now Iridium plugs in a 2.2L Cavalier, 3 older generation Northstars, a baby 4.0L Northstar (Olds Aurora), an LT1 and LT4 Corvette, a 4.2L Trailblazer, a 6.0L Escalade, and I will likely put them in my 4.2L Audi V8 when the time comes. I had good results with all of those engines using non-Delco plugs. For the most part, a spark plug is a spark plug as long as you get a similar/same heat range.

I didn't try the Bosch strictly because of the 4 prong, 'gimick' but because with 4 ground paths I figure that as one wears out then the spark will jump to the next ground that provides the least resistance. Also, I thought about the old days when engine builders used to index the plugs. With the open shroud design of the +4 plugs I figure that is eliminated when the plug is central to the head.

I've been very happy with the Bosch +4 plugs and continue to use them.

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what was GM thinking with mounting that Air valve on the rear valve cover?

Yeah, I know what you were thinking. I thought the same thing when I changed the plugs on my 03 STS. I ended up bending the mount out of the way and just leaving it there to make the next plug change easier. LOL

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In all my years of replacing plugs, the only time I've ever remotely noticed a change was on my old lawnmower!

Same here, except new plugs ran better in all instances except one where the plugs weren't worn. I figure as long as you get the right heat range, a plug is a plug. The car doesn't know whether you have Delco, Champion, or Bosch plugs in it. As long as you have a good spark path then you get ignition.

I did have one bad experience about 20 years ago with plugs and that was GM's Rapidfire plugs. They had a star shaped electrode which I thought might be good (I was a kid). They were great for about 10K miles then they were worn out. I don't think GM sells those anymore.

KRSTS
08-27-13, 09:02 AM
I'll stick with the OEM platinum thank you.

Subsailor613
08-27-13, 10:58 AM
The Northstar engine, has been in the GM family for a long time,
they have tested everything on it, and changed things to further
help the engine, IF plugs last for: 100,000 miles,on a certain brand,
I would NOT change them to another brand. JMO= Just my opinion.
They have proved themselves. Really, what would you gain ?
AND, even at 100,000 they still perform pretty damn good !
A lot of people do NOT realize, spark plugs have a HEAT RANGE,
and a certain plug size, DOES come with a bunch of heat ranges,
to accomodate different drivers, and conditions.
Normal, Hot, Cold, and various degrees in between.
When changing plugs, it is recommended to "READ" the old plug,
The perfect heat range is a chocolate color.
Sticking with the factory recommended HEAT RANGE, is chosen
by the manufacturer for various conditions, for the plug to last
and NOT self destruct, or Harm the engine.
For Instance: a plug TOO hot, will burn a hole,
in the top of the piston.
Happy and Long Motoring.
:cool2::bulb::thumbsup:

EChas3
08-27-13, 09:58 PM
If it works, don't fix it.