Just had the factory plugs changed to Autolite Platinum at 48K on a '98 4.6 4WD (2 hours shop labor, plugs 1.99 at Schuck's). They all wore very evenly, but they were WORE OUT! The electrode was almost worn down to a stub on all the plugs about the same.

Should definately notice a difference in towing power and fuel economy pulling two ATV's.

Also needed a new serpentine belt (almost $60 w/tax at NAPA, installed myself). He said it was as big as the ones they use on Kenworth's !! 99 inches long if you have AC.

Just thought I'd pass this along as piece of mind "FYI".

 

Might have considered double platnium..
Because the ground electrode wears out..
Doubles will prevent this....
I never let my plugs run further then 40K..
You start losing performance and fuel economy. So it pays for itself to change them and while you are in there..minds as well put the best in....

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2000 F250 PSD Auto 19+mpg PIII propane exhaust Ramair ThermoWrapped
2001 SuperCrew 4.6 auto 19+mpg K&N
1969 Mach1 351C 4spd 3.50 LS Autocrosser

 

Just a thought, you can get a Goodyear Gatorback belt from Summit for around 35 bucks, it's got a lifetime warr.

 

I plan on having mine changed 30 seconds before my 3/36 warranty runs out -- figuring that I can afford the labor -- and/but if the threads strip it will be on Ford's bill, not mine.

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Y2K™ Jim - N8JG@Hotmail.com

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"