Whitehorse10

I gotta go with the "change them early" crowd on this one. I'm not waiting until 100K miles to change plugs, I don't care how good modern engines are. I change mine every 30K regardless. They aren't expensive and it's good insurance against future potential problems.

30K, change plugs, change coolant, change gear oil, change tranny fluid and service tranny. It's just good vehicle maintenance.

teetertotter

I thought I would reopen this thread. Another thing you might want to know in talking to racing people in dealing with STOCK engine...etc... go with the single electrode platinum vs the 4 electrode. There is no advantage. Save your money. I went to Nappa today to replace my wires at 103,000 miles with OEM type as there again no advantage to upgrade to 9mm in talking to these people, to make long story short. It is like changing oil, if you want to change at 3000 vs 6000+ conventional oil go ahead. Independent Lab tests show conventional oil does NOT begin to break down until 5000. But many want to change early which is just fine. My 98 Grand Prix went 118,000 miles b/4 changing plugs and still got same mpg. Talk to your buddies that race at the track, you will learn a lot about engine and brakes and whole bunch of other things on stock and not stock Mustangs. Street machines, stay with the manual, from what I hear over the years. Know worries. Good luck with changing your plugs as often as you like, for those folks!