About a week ago I bought some Autolite Double platinum spark plugs for my '96 GXE. After discussing this with some of you, I found out (the hard way), that my car needs the NGK's. My car started having rough idle this past weekend. So, I replaced those Autolites with some Copper NGK (BKR5E-11).
Anyway, to make a long story short -- the car's rough idle went away--so far. May have been the Autolites, maybe not... who knows? At least, now I feel better that I have those NGK's
Also, I noticed that some of you believe that the stock platinum NGK's are worth the extra money. Well, I emailed NGK prior to buying the copper's and this is the email they sent back:
"All NGK spark plugs have copper cores or nickel cores. The platinum and iridium are used on the firing ends for longevity not in the core of the spark plug. The BKR5E-11 has a copper core, however the firing end uses nickel alloy rather then precious metals. The longevity will be less and the ignitability won't be as good as the fine wire platinum and iridium spark plugs."
NGK Technical Customer Service Representative
Name of this NGK person has been withheld for privacy reasons.
Anyway, I thought I would share this email with you all as I thought it said a lot. It should make some of you mad (those that spent the extra doe on Platinums) and it may make others of you sad (for the others who bought the platinums)