Spark Plug Brand

[CottonTexas]

Agreed, go with OE when possible for best fit.  GM's (typically) got Denso from the factory, AutoLite makes Ford's Motorcraft, Champions for Dodge/Chrysler, and a lot of imports use NGK's with the exception of the Euros which mostly used Bosch.  I'm with Wake on the iridium plugs, but they aren't available for everything, and can be costly.  Mulit-pronged electrodes aren't typically worth their money since the spark usually finds a favorite path and keeps hitting the same spot every time anyway, and if you're going platinum, I'd say go for "double platinum" (they plate both electrodes) so you get the full benefits of platinum reliability.  These are all my personal recommendations, but as per PineyCruisin's situation - A spark plug's a spark plug, and they should work across brand-lines.  NGK's are notoriously reliable, but I don't think it's beyond them to make a dud every once in a blue-moon, however their QA is pretty tight.  Just my 2¢, Cotton

P.S. TIP: Do not gap iridium plugs.  

 

[highdesertranger]

GM = ACDelco. highdesertranger

 

[PineyCruisin]

These are all my personal recommendations, but as per PineyCruisin's situation - A spark plug's a spark plug, and they should work across brand-lines.  

And that's exactly what DH thought when he purchased the NGKs. When we called the shop to inquire about the problem, the mechanic also told us that he has seen Chevy's work OK for a while on another spark plug brand but then start sputtering out of the blue many miles later with the owner bringing it in thinking it was a more major engine problem. Switching out would fix the problem. If I didn't hear the mechanic predict the problem and solution before the switchout, I wouldn't have believed it myself. 

We had also wondered if we merely got a defective plug and that switching out had merely replaced it with a good one (brand not withstanding). But, because it was multiple cylinders misfiring, the chances that more than 1 of the 6 plugs were defective are even more slim (and he was sure not to gap the plugs at all since they were iridium)

I"m now a bit curious to find out what are some inherent structural/material/composition differences between plug brands to account for what we just experienced.

Still don't understand it fully .....(updated to add: just thought of something....maybe the gapping preset on the iridiums are what is causing this???)

 

[CottonTexas]

GM = ACDelco. highdesertranger

AC Delco = GM replacement parts
Denso = GM factory OEM

Cotton

 

[CottonTexas]

After I thought about it for a minute I figured I should probably elaborate on my previous post, so lemme take just a second here to explain:

HDR is right.  AC Delco is a GM company that makes replacement parts for GM vehicles (as well as other makes), and is geared towards common replacement parts.  However, while it is a division of GM, these parts are not typically what was used at the factory.  Notice that the pic above has two part numbers: One is the Delco PN, and the other is a GM PN.  This is so that they can be found through either catalog system; GM Parts by the dealership or AC Delco parts by retail vendors.  I know it isn't a spark plug, but having both PN's on the same box made it good for illustration.

What I recommend (Denso) is the same product that GM used at the factory, making them a sound alternative to Delco's, which could be a cost savings to those looking to be frugal without sacrificing quality.

Cotton

 

[jonsun]

I always use NGK, Nipon Denso, or Bosch plugs. When I don't care, I'll use Autolite.

I used to think that too but we got a sponsorship from them so we get the plugs free. They're pretty good. It's like a 700hp small block Chevy engine with super duper MSD ignition....but they are changed often.