Pontiac G8 2008-2010 - Replaced my spark plugs

I just replaced my spark plugs in my G8 with some Bosch Iridium's. They seem okay so far. I'm not sure how they compare with the ACDelco stockers, but I'm definitely seeing a slight improvement in gas mileage, though it still may be too early to tell. Throttle response seems slightly better as well. I'm only at 44k miles, but I replaced them anyways. My plug wire boots were stuck on real good too! Required quite a bit of pulling force to pop those things off. Anybody else tried Bosch plugs?

Any word on this? I want to do mine soon. I priced ngk platinums from autozone, 3.09 a piece when i called o,reillys they said the car has to have iridiums. which were 7.49 a piece. any suggestions?

Has to have irridum huh? That's stupid. You can run a cheap ass TR6 in it and you would never know the difference. You won't get 75k miles out of them but they will work just fine.

I was under the impression that the more fuel burned and not left over, the better combustion and cleaner the burn is, preventing left over from becoming sludge over time... But I could be over thinking it. It most certainly will work with cheaper plugs, but the combustion might not be as equal, thus making a fraction less of power. Last I knew, I wouldn't skimp on a few dollars for slightly lower quality.

I was under the impression that the more fuel burned and not left over, the better combustion and cleaner the burn is, preventing left over from becoming sludge over time... But I could be over thinking it. It most certainly will work with cheaper plugs, but the combustion might not be as equal, thus making a fraction less of power. Last I knew, I wouldn't skimp on a few dollars for slightly lower quality.



Get the correct heat range in copper, platinum, or iriduim and they will work fine. Pt and Ir aren't "better" plugs because they cost more, and they don't increase spark. Copper is a better conductor than both of them, but it is also a softer metal. The Pt and Ir plugs last longer due to their hardness and properties of being nobel metals. A longer plug change interval is the only benefit to using them. They cost more because the raw material costs more.

The other aspect is that just because a plug still fires at 60k or 100k miles doesn't mean they are still at their peak. So yes, a plug change at a lower interval could very well restore power. Our G8 has a slight miss at idle with 40k miles. I'll be changing wires and plugs before too long, and I'm not wasting $ in Ir plugs if I'm only going to get 40k miles out of them.

NGK TR6 plugs pulled after 20k miles... they were completely worn out. Insulator on the plug for #7 was the worst of the bunch. Switched back to AC Delco Iridium, won't have to worry about that for awhile.

As a rule of thumb, I always put in the plug that the manufacturer put in the engine originally. I've heard nightmares from many people that have switched out of a Delco or NGK to a Splitfire,Bosh or E3 plugs and lost MPG or caused engine miss fires. I paid $60 for 8 AC/Delco Iridium plugs wholesale/Retail probably $75-80? Too cheap a part in my opinion to play around with.

The spark plug wires are where GM can really improve. The OE wires tested at .784 ohms resistance while aftermarket $85 Taylor or MSD wires test at less than 1/2 of that at .374-.380. I think Granitelli and a few others test near .000 ohms resistance,but RF interference becomes an issue.

Just my .02

Using what GM does isn't always the best either. My 00 SS came with Denso platinum plugs as did other LS1's. GM just grabbed what they got a deal on when they had supply issues. The platinum puck on the ground had fallen off of several of my plugs. I pulled them around 35k miles so who knows when it happened. This not only made the gap huge, but dropped metal into the cylinders. While it didn't hurt anything except power and efficiency, it showed me that GM uses parts that are cost effective, not best. The weak 7.5" 10 bolt being used in 4th gens screams that too.
In my LS1, I ran Bosch platinums (the regular electrode) while stock and cam only, TR55 while cam only. I also ran TR6 and Autolite 104 with the 408. Plugs never caused an issue when changed at regular intervals. I also ran cheap part store plug wires for a while and ran my best ET.

Stick with a standard electrode design, decide which material you want (longer change interval for more $ or shorter change intervals for less $), choose the correct heat range and a decent plug manufacturer and all will be well.

I just changed mine used the Bosch radium and I noticed a difference an extra 4 mpgs. and little bit more power it feels like. They were pretty easy too bout 45 mins. while I was at work.