Mike,
I cant speak to the life expectancy of the fluid from the factory, however I know from track experience that old fluid will absorb water and severly lower the boiling temp. This (water) will cause corrosion within the system and can cause brake failure under severe braking conditions. I found the later out the hard way this fall while at the track in my wifes 911. I had neglected to change the fluid before we left (it was fine 60 days before at another track) and found out the true meaning of brake fade... at 120+mph heading for a 90 degree right...foot to the floor! I was able to negotiate the corner and slow the car by pumping the brakes and downshifting. Needless to say I slowed down and took it to the paddock.
Other than the problem of corrosion in the system (long term) the only way a truck would experience similar heat would be during extended braking, probably loaded and downhill.
Except for the Porsche I have never changed the fluid in any other vehicle...and dont expect to have to in my truck.
Just my opinion...
\'03 GMC DMax/Ally 4x4 Crew, Jet black, Factory dual alts, ARE Z-series cap, Jotto desk, Pentium Powered, Lots on the way...933 miles 1.5 weeks old! I\'ll give GM one last try...<p>\'01 2500 DMax 4x4 xcab, JET BLACK! Chipped, straight piped, 265 Wrangler MTR, stainless nerfs, Lund deflectors, Polished aluminum American Racing rims/stainless caps and lugs, Bedslide, Line-X, Powervision, Advanced Cover, 3000 watt power inverter, 4 corner strobe kit, Jotto Desk computer stand with 1gig Dell Inspiron laptop/docking station with CDRW/DVD and Voice activated GPS and Color printer. Lots still to go. - Gm is buying this truck back...Lawyer is now fighting with GM...new chevy front end is hideous!<p>\'99 Powerstroke-103k abusive miles with no problems. Truck is sold!<p>1990 Carrera 2 Cab black of course, Koni/Eibach adjustable suspension, Zimmerman vented rotors with racing pads, \"cup\" style airbox mod, harness bar with video camera mount. very fun track/street car.<p>\'01 Volvo XC-wifes\' truck-not bad for a go-go-grocery getter.<p>PULL MORE, GO FASTER!