which is the best replacment sparkplug for my Alpha? GM, Bosh and etc...

 

I don't know about the V8's but when I swapped out the plugs in my 5 cyl. they looked like I could have just regapped them slightly and reinstalled them for another 100k of service. In any event, I just replaced them with new OEM Delcos.

 

41-103 ac del....5cyl. or what ever you like.
Chris

 

I believe the plugs for the H3 are Iridium suggested, so if you get Delco, Bosch or whoever I don't believe the electrode design is different between each company because of the Iridium.

 

copper, platinum, 2x platinum, or iridium... its all about longevity. Do you enjoy working on your hummer? If so you can use anything. The copper plugs are the best conductors, but short lived with the "cop" system. Platinum & iridium plugs do not deteriorate as fast. Go with the acdelco iridium plugs, first choice (around 6.00ea @ Napa), or if they have a sale on Autolite 2xplatinum like my local Napa did @2.99each, they will perform just as well as the iridium plugs do.