Plug change on my 6.0L

jmassi · August 8, 2014

Ok, I'm gettin' close to 100K on my 2500HD, looking to change the plugs and wires. Current plugs are iridium, 41-985. I had the local dealer say that they recommend using platinum plug since there have been issues with the iridiums. Anyone know about any issues with the Ir plugs? I'd like to put the same plugs back in, truck been running like a champ since new. I believe the 41-985s were superceded with 41-110. I checked the plugs and they look pretty good, no gunk or anything.

kstruckcountry · August 8, 2014

You should stick with the Iridiums, I haven't had any issues in my 5.3 with them... I believe they went to a different gap and that's why the number changed.

00Silverado4x4 · August 8, 2014

Never heard of anyone having any problems with the iridiums. I would stay with those, I did, can't complain, got about 30k on mine so far. Yes they were superceded by the 41-110. I'd still check the gap on them out of the box prior to purchase. They are suppose to be factory set and non-adjustable.

desrtrat · August 8, 2014

Ok, I'm gettin' close to 100K on my 2500HD, looking to change the plugs and wires. Current plugs are iridium, 41-985. I had the local dealer say that they recommend using platinum plug since there have been issues with the iridiums. Anyone know about any issues with the Ir plugs? I'd like to put the same plugs back in, truck been running like a champ since new. I believe the 41-985s were superceded with 41-110. I checked the plugs and they look pretty good, no gunk or anything.

this may help..

Subject: Information on New Spark Plugs and Gapping #03-06-04-060 - (10/24/2003)

Models: 2004 Buick Ranier

2002-2004 Cadillac Escalade, Escalade EXT

2003-2004 Cadillac Escalade ESV

2004 Cadillac CTS-V

1997-2004 Chevrolet Corvette

1998-2002 Chevrolet Camaro

1999-2004 Chevrolet Silverado

2000-2004 Chevrolet Suburban, Tahoe

2002-2004 Chevrolet Avalanche

2003-2004 Chevrolet Express, TrailBlazer

1999-2004 GMC Sierra

2000-2004 GMC Yukon, Yukon XL

2001-2004 GMC Yukon Denali, Yukon XL Denali

2002-2004 GMC Sierra Denali

2003-2004 GMC Envoy XL

1998-2002 Pontiac Firebird

2004 Pontiac GTO

2003-2004 Hummer H2

with 4.8L, 5.3L, 5.7L or 6.0L V-8 Engine (VINs V, P, T, Z, G, S, N, U -- RPOs LR4, LM4, LM7, L59, LS1, LS6, LQ9, LQ4)

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A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used.