Louie

well... the title says it all...

theedge67

Owners manual says 100,000 miles for normal driving conditions. Consider earlier if you drive extremely hard or have crappy fuel in your area.

94tbird

i repalced mine at 20k but that was because of a certain modification i made to the car haha

Louie

Ah yes, because of the louvers!

06GT4RAD

I personally would change them out at 40k. I have seen to many problmes with leaving them in for 100k.

RIchard

Torch_Vert

100K seems pretty sappy to me, especially considering plugs are not exactly a high dollar item. I'd rather swap them more often and be sure they're in good shape. At the very least pulling them for a visual inspection every 10K or so makes sense imho.

theedge67

Depends on what kind of driving you do too. If you drive a lot of highway miles and are easy on the go pedal, you'll be just fine going 100,000. If you take lots of short trips, or use it as a weekend driver with not many miles per year, consider changing a little earlier. With the platinum plugs, they last much much longer than the older standard plugs, especially with the newer cleaner fuel. These cars burn so clean with no oil burnoff that changing plugs early is a waste of time and money really.

Rash

You might find this interesting:

http://www.mustangforums.com/m_1952916/tm.htm

06GT4RAD

Sorry but that simply is not the case. The Auto makers would love for you to believe that but trust me when i tell you DO NOT leave your plugs in for 100k regardless of how you drive. I have seen to many cars and trucks both that have not been able to get the plugs out from the head and also I have seen plugs with the entire electrode burned off and the customer seemed to think the car was running fine. At the least change or check your plugs every 40k It is cheap insurance.

Richard