I have a 2006 Silverado Crew Cab LT3 with 33K. No problems with it or codes but i pulled 4 spark plugs and gap measured .037-.038". Manual says should be .040". Should I regap? Plugs are OEM AC Delco 12571164 - 41-985.
Also the 8th digit of my VIN is Z which I find to mean a 5.3L Flex Fuel engine. I didn't know my engine was Flex Fuel. Is this correct.
I'm think of replacing plugs as my MPG isn't what I would expect and I am a very lightfooted driver. Is AC Delco the way to go or another brand?
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z means flex fuel capable. not that you have to run it. but yes its flex fuel capable. as far as the plugs, i'd regap and replace and look elsewhere for your mileage problem. if you do decide to replace them, some people swear by bosch, some by e3 or whatever, i personally go back with factory plugs on a stock engine.
rip: 2002 silverado 2wd 4.8, , airaid mit, trans dapt tbs, redneck ram-air, ravin muffler, no cats, dual 4" tips, 265/75/r16 cooper discoverer s/t
gone: 1989 GMC Jimmy fullsize, carb 350, TH350, NP203, 33x12.50x15 BFG All Terrains, front and rear lockers
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Join Date: Apr 2009
Those plugs should be good for 100K miles, but if you already have some of them out then I guess it would be a good time to replace. I vote for the factory plugs. All those gimmick plugs are a waist of money IMO. Also don't worry about the flex fuel crap...I had a Suburban that was flex fuel and I ran some of the E85 garbage in it for one tank and it ran rough and the mileage offset the cheaper cost of the gas. I never ran it again.
__________________ 2003 Chevrolet Tahoe 4X4 5.3 2002 Chevrolet 2500HD 4X4 8.1 - BlackBear Tuned
They are puttin iridiums in now cuz they have low resistance and take less voltage to fire. Arcing is what wears metal out between two contact points. The NGK's I suggested are iridiums. As mentioned before, iridiums are made to last 100k before replacing.