At 100,000 miles it must be time to replace the spark plugs in my 03 Tahoe. Any issues with installing cross referenced Bosch brand in place of the OEM AC Delcos? Thanks, OLDED

I dont like Bosch, personally. Have had the best luck with delco replacements and recently used NGK plugs in my chrysler and am happy with them. Ran bosch in my monte carlo and promptly removed them. Mileage sucked, performance (what there was) dropped. Put the Delcos back in and was a happy camper. Just my personal experience.

Put the Delcos back in

I've heard Bosch are harder to fire and can stress the rest of the ignition system causing premature failure in other components.

Why change them? Are you having issues? I put 200000 miles on a 2000 Silverado and changed the plugs just because. They had worn about .002"
If you decide to change them, stick with the Delcos.

Ed,
It would probably be fine, but I also do not understand why you would replace a part that has given you 100k miles of troublefree operation with a different brand with unknown performance characteristics.

Glad I asked, I'll stick with the OEM's. Thanks for the replies. OLDED

If you look close at your factory AC Delco plugs they are actually NGK units made in japan. Plugs in my 2003 Suburban are AC Delco part # 12567759 also on the same plug in small print is NGK PZTR 5. These plugs are a iridium plug.

If you look close at your factory AC Delco plugs they are actually NGK units made in japan. Plugs in my 2003 Suburban are AC Delco part # 12567759 also on the same plug in small print is NGK PZTR 5. These plugs are a iridium plug.

I would not go Bosch.

I have run NGK TR55s in my Corvette LS1, and LQ4 6.0 2500HD. The LS1 forums really debate the gains from a iridium plug. It doesn't hurt but the regular plugs have run great on a daily for 40k miles and many of the power adder guys run them too.

OLDED Advance or Autozone carries the NGKs for ~$2 a plug IIRC locally. If you change wires stay with the OEM, MSD, or the GMPP wires.

i would pull them at 100k,brush a little neverseize on the threads only ..and reinstall for another 100k.