Engine/Transmission (1998.5 - 2002) Overdrive

[Rockcrusher]

To overdrive or not to overdrive.

With the high cost of fuel now I'm looking for the best milage towing. With my old fifth wheeler I gross out at about 12,000 lbs.

In the past I've used overdrive on flat ground, 55-60 mph and not on hills.

Of course in overdrive its much quieter and better speed.

I have always understood diesels perform better at higher rpm and not being "lugged". Without towing truck runs great at @2000 rpm (70 mph).



Which is better, tow without overdrive or use it?

Planning a cross country trip and hoping to get at least 12 mpg.

My old 1990 would get 15 easy towing, but my 2002 is lucky to get 17 unloaded.

 

[B.G. Smith]

I just traded a 99, I couldn't tow in OD below 65 or the torque converter would slip/chatter. I would think that if you drive 55/60 that your fuel mileage would be as good or better out of OD. bg