So what spark plugs do you use on a 5.3l and why?

h2ofwlr · June 19, 2014

Curious what you all think. I have read some guys love platinums, some like the split fires for better performance and gas mileage,e tc.. And of course some say stick with the AC Delco.

So what are your thoughts?

02suburbanZ71 · June 19, 2014

Ac delco because i had 123K on my factory plugs

txab · June 19, 2014

Spitfires are worthless. Stay OEM.

Iridiums have a longer life, 100k miles, than platinums. If your rig is older and lots of miles, platinum or double plats might be the way to go money wise. Many people run copper plugs and report no problems, they just don't last 100k

Edited July 14, 2014 by txab

Daryl Z71 · June 19, 2014

ACDelco in every GM I own.

dgood · June 19, 2014

Unless you're racing, stick with the revised spec, the Iridium plugs (they are actually NGK OEM)

The platinum plugs were superceded in 2003.

GM P/N 12571164 with AC Delco P/N 41-985

old thread here also:

http://www.gm-trucks.com/forums/topic/53417-ac-delco-spark-plugs/

Duelin · June 19, 2014

Always OEM. GM and other manufacturers spend millions of dollars developing and testing to get the correct spark plugs for each individual engine application. How much do you think other spark plug manufacturers spend on developing and testing each individual engine application. Or do you think they just try and duplicate the OEM plugs? One thing comes to mind. When I started to work at GM in the early 60s I started on the motor line. One of the first thing they stressed was to torque the plugs to the correct specs.. If the torque was not correct it could change the heat range as much as 2° in either direction.

Chris · June 19, 2014

OEM AC Delco unless it is a bossted or nitrous application.

Edited June 19, 2014 by Chris

j-ten-ner · June 19, 2014

...If the torque was not correct it could change the heat range as much as 2° in either direction...

That's interesting.

How come?

so long

j-ten-ner

Duelin · June 19, 2014

My understanding was so the spark plug would transfer the correct amount heat that it was designed for.

butzers09silverado · June 19, 2014

OEM unless it predates fuel injection, lol.

white1500 · June 19, 2014

I'll be going back to ac delco when they're replaced.

royesses · June 19, 2014

ACDelco Iridiums. Long life and engineered for the application

00Silverado4x4 · June 19, 2014

I stay with AC Delco. My GMs always run best on them. I had 107k miles on my factory plugs & they still looked pretty good.

trapperman83 · June 20, 2014

The auto light iridiums are what I run basically factory replacement.

JRB1953 · July 13, 2014

An additional question I have on this is what would cause the factory plugs to burn to .090? I just replaced the factory AC Delco/NGK Platnium PZTR5A 15 with NGK Irridium TR5IX 7397 on my 2003 6.0L GMC 1500 HD at 112,000 miles. I researched and found the factory plugs are gapped at .060. The irridium are gapped at .040. The old plugs were burned to an average gap of .090. The threads on all old plugs had a gold tone on them. The truck didn't run too bad, rough idle every now and then, but fuel mileage sucked. Is this normal or is there something wrong with the old plugs being burned that much? Thanks.