Spark Plug replacement. Really 100k?
Thread Starter
Drifting
Joined: Aug 2002
Posts: 1,857
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From: Yakima WA
Spark Plug replacement. Really 100k?
I am sure this must have already been discussed, so a couple of knowledgeable answers will suffice. The owners manual on my 01 coupe says to replace plugs @ 100k. Is that realistic? I guess they wouldn't say it, if it weren't true. How many of you have 100k on your C5 & did you wait that long?
Safety Car
Joined: Nov 2003
Posts: 4,979
Likes: 5
From: San Diego, CA "leaf" "tee" "e"
The plugs will last that longs, but they'll be caked under lots of carbon, and the engine will run like crap. If you're really cheap, take them out and clean them. Better yet, replace them with copper TR55's. They will need to get replaced every 30K miles, which is about as often as you should clean the plugs anyway, but you'll get more power, better fuel economy and better idle compared to platinum plugs.
Resident moron
Joined: Jun 2003
Posts: 4,746
Likes: 20
From: Assachusetts
Not my C5, but my daily driver Camaro has 77k on the original plugs and the car still idles and runs fine. No misfires of any kind.
I will probably swap out the plugs this summer at about 80k or so. The main reason is that I want to be able to get them out, and not have to worry about them being seized.
If you don't go for every last HP and you don't mod your car, 100k is pretty much fine.
Dope
I will probably swap out the plugs this summer at about 80k or so. The main reason is that I want to be able to get them out, and not have to worry about them being seized.
If you don't go for every last HP and you don't mod your car, 100k is pretty much fine.
Dope
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
I personally would never allow a plug to stay in that motor for 100K, but then I change my oil at 4-5K, not 7K or 10K (I let the DD Corolla go to 7.5K, but I run HQ synthetic in that as well).
One thing I don't see mentioned here is the stock GM plugs have (or had) platinum "pucks", and these will fall off the end of the plug, and your motor will eat them. Maybe they will make it past the exhaust valve o.k., maybe they won’t!
When I got my car at 13K, that was the first "mod" I did.
One thing I don't see mentioned here is the stock GM plugs have (or had) platinum "pucks", and these will fall off the end of the plug, and your motor will eat them. Maybe they will make it past the exhaust valve o.k., maybe they won’t!
When I got my car at 13K, that was the first "mod" I did.
Safety Car
Joined: Sep 2001
Posts: 4,411
Likes: 1
From: Wilmington NC
Originally Posted by dbwade36
I am sure this must have already been discussed, so a couple of knowledgeable answers will suffice. The owners manual on my 01 coupe says to replace plugs @ 100k. Is that realistic? I guess they wouldn't say it, if it weren't true. How many of you have 100k on your C5 & did you wait that long?
The stock Delco plugs had a real problem holding on to the platinum insert on the negative electrode. See the photo. The top plug is missing the little "puck" this is fairly typical. My experience has been I haven't seen a C5 with the original delco plugs that had all the inserts. Without the insert you are running a wide gap and don't have nearly the plug life.
You may want to change to iridium plugs. This is now standard on late version C5's. I used NGK TR55IX. Iridium is very tough for long life and has a smaller profile in the combustion chamber which allows for more flame exposure to the fuel mixture.
www.sparkplugs.com for more information
Drifting
Joined: Jun 2000
Posts: 1,754
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From: Redwood City Ca
I changed plugs and wires on my '99 coupe at 45,000 miles, and immediately noticed that my car revved faster, and had more "pep" to it. Your plugs will last 100,000 miles, but for performance purposes, I'd change them out a lot earlier.
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Burning Brakes
Joined: Oct 2003
Posts: 922
Likes: 2
From: Resume Speed Tennessee
Gordon Killebrew says the closer you get to 100K, the closer you are to having a seized plug that will rip the threads out of the head. He advises changing plugs in aluminum heads every 30-40K, and use anti-seize.
