Hi,
I got around to checking the plugs on my 2002 C5 today. They are platinum DENSO PTJ16R15’s not AC 41-952’s as the shop manual states. After hearing about the AC’s losing their pucks, I am glad the car didn’t come with AC’s. These plugs are their PLATINUM long-life plugs not the U-GROOVE or the IRIDIUM plugs.

"Platinum Harder and stronger than nickel it is commonly used in vehicle manufacture for its long-life properties - especially for plugs in hard to reach positions. Expected life is approximately 100,000 km in a passenger vehicle. These DENSO plugs have a 1.1mm center electrode."

My car was built in August 2001.
Bye for now,
Steve
:seeya
http://www.denso.com.au/dw/spark/spark_gen.htm#techinfo

 

Yea, they are pretty good plugs. GM started putting them in Vettes sometime prior to Jan 18, 01', when mine was built. I recently replace mine with NGK's but the Denso's still looked good. :cheers:

 

NIPPON/Denso spark plugs in AMERICA'S Sports Car :( ...i got 'em too...still waiting to put in my AC/RapidFire #12's...anyone put these in yet??? :chevy :seeya

 

Replaced my AC's at 38,000 miles all the pucks were gone, gaps were all .065 or more. Replaced them with NGK 55's ran much smoother, all for $1.65 a plug. I would rather change these out yearly than try to make a much more exspensive plug last a long time. Changing plugs on C5's is EASY! :reddevil

 

When I bought new plugs from my dealer, they came in the usual AC box with an AC part number on the outside. But when I opened the boxes, the plugs said "Denso"