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I have a 1999 Infinity motor home with a Ford V-10. It has 34,000 mi. I have never changed the spark plugs.

It still runs fine and fuel mileage is constant at 7 mpg.

I have heard horror stories about the spark plugs being changed and damaging the threads in the head.

Can anyone give me some first hand information about changing the plugs.


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Buying a good Sears Craftsman sparkplug 5/8 socket with foam inside to hold the plug firmly is a good start. Next you want to obtain a packet of anti-seize compound to put lightly on the plug threads so they will be easy to take out next time and lubricate the threads when you put the plug in. The major damage to threads in the cylinder hole is caused by using a ratchet on the plug socket to start the plug in the hole. If you hold the extension to the plug socket in your fingers and hold it straight and turn it slowly by hand until the threads start you will not cross thread it. If it gets tight right away then it is crossthreading so stop and unscrew it by hand and start again. Like I said if they get tight right away then stop. It is only if you use a ratchet and they get tight and you keep going that you will damage the threads. Also the anti-sieze compound on the threads acts as a lubricant to help them go in. On our race car we change plugs twice for each race. Once for the warmup and then for the race. We do this 6-8 times a day and never damage a head. We always start them by hand. My recomendation is to get double platnium Autolite plugs as the replacement and they will go on for another 60,000 plus miles. If you run into a problem when doing it then stop and let us know and we can help you.

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