Prbly ax delving if Chevy could make an improvement at the time they would have given the gas prices and a poor rep.
denso plugs denso plugs
AC Delco
A 2004 Chevrolet Trailblazer that has a 4.2 liter engine will have a spark plug gap of .044 inches. The best spark plugs for this vehicle are iridium spark plugs.
Champion rc12lyc
A/C Delco and put the # in it that it calls for from the factory.
Disconnect the spark plug wires from the spark plug( best to do 1 at a time, so not to mix the wires). Using a 5/8 socket you can remove/install the spark plugs. Gap should be .035" and torque is 24ft-lbs.
You have to use platinum-tipped spark plugs ONLY.
NGK laser iridium spark plugs.
the best spark plugs for all ford vehicles are the motorcraft type, which they come from ford.
The best spark plugs are the original equipment plugs that were installed by the manufacturer at the factory. Sometimes you may need to go to a dealer to get the exact plugs.
Champion SPRE14MCC4. Those are the stock and work just great.
AC plugs