Yea, that's why Astin Martin developed the entire Ecotec engine around those iridium plugs and Saab continued with that design , and it's been working great all these years.

 

100,000 for plugs is BS. Doesn't work and will cost extra money. The bigger the plug gap gets the harder the ignition has to work to get current to the plugs. You can cause problems with the Turbo being intermittently inoperative. A side note; You always have to be 100% sure you buy parts that are for an SS. I was sold plugs for an HHR standard model, not the SS. and had a Turbo that seemed doomed just 6K later. Changing the plugs cured it, as the plug gap grew too large. Just like 100,000 miles could do.
Whenever I hear the 100,000 plug life story I always counter with my experience as a fleet manager of 36 Chevy vehicles with Vortec V8's. As they aged out toward 100,000 miles we started having problems. One had to be towed in because it had a dead cylinder. One plug coil was burned out. It was replaced, fired up the engine and it started missing right away. Tech then pulled the plug which had a huge gap. All plugs were the same way. All replaced. Next day same vehicle went out of service with a miss again. Found 1 plug wire internally burned out. I started flagging all vehicles that had 80,000 miles and we replaced wires and plugs. Out of the 36 units 3 we had to almost resort to a torch to get the plugs out. Meantime 2 more had to be towed in that got about 85+K on them. 32 vehicles were normally in service for 16 hours a day with 4 more on another 8 hours all night. The expense of running all to 100,000 miles with towing likely, possible ruining some Cat Converters in the process would ruin the budget. LOL.

 

Fact:
Many HHRs have never had the plugs changed.
I have a set on my shelf with 200,000 miles on them that I would not hesitate to use, if needed.

Perhaps you should try using the OEM Iridium plugs. For SS ACDelco 41-108, for most other HHRs 41-103. The Iridium whisker does not wear away like "traditional" plugs.
I recommend only those plugs.

 

Nice, I completely built a 61 Baja fun little cars to tinker with.

 

Ok, change the original iridiums at 75k if you like. Or 50k. But use the iridiums.

I changed an original set at 95k in a 2.2 and the gap was maybe .001-2” over and the car was running fine. Quite sure I could have just put them back in and gone another 100k. But I wasn’t pulling any trailers.

I might consider rutheniums, but why? Longer life?

Also, for hard-running fleet vehicles, I might considered a slightly colder plug. Detonation can break a spark plug in seconds, not XXK miles.

 

100,000 miles is a suggestion, not set in stone, it’s your choice when to change plugs, I do know anything but the 41-103 iridium plugs don’t do well in these Ecotecs , I’ve tried other brands and switched back to OEM plugs.

 

is is 41-103 or 45-103? I have seen both numbers in various posts so I am very confused which doesn’t take much these days. Should I put anti-seize on the threads? I remember doing that on a lot of my aluminum headed vehicles. I have an 07 2.2l auto and 288k miles. Thanks.

 

I don't know what 45-103 is. GM says no to anti-seize, others say yes. Do what you want.

 

45-103 ? Musta been a typo, I don’t see that number in this thread.
To confirm for future readers AC Delco 41-103 iridium spark plugs, anti seize is optional, torque to just 15 ft lbs , no more! Or finger tight then 1/8 of a turn! If you don’t own a torque wrench.