Hey i have a 02 ram 1500 4.7L v8, i was wondering when it was appropriate to use the overdrive function in my truck, i read the manual and i couldnt understand the load of bull**** they said. Rite now i am driving with overdrive off in the mornings and whenever i start up my car, i also like to turn it off when i want to really push the rpms n get up around 85. Am i harming my engine? SHould i always drive with overdrive on? Or can i just switch in and out of overdrive when ever i feel the need to get going fast?

 

As I understand, the vehicle will disengage overdrive if the vehicle is not warmed up.
When going at a constant speed, the transmission will shift into over-drive around 30-35MPH. So... if you do a lot of city driving, stop 'n go's, its a good idea to disable overdrive. The constant shifting into and out of overdrive can cause wear (as you would imagine).
If you drive highway, I would just leave the O/D alone. It will downshift as needed. If I'm not mistakened, I believe your 4.7L may have the (5)45RFE. If so, that transmission has a second 2nd gear (called 2nd prime). This gear is used as the knock-down gear, for when your cruzin on the highway and wanna pass Grandma.

So, to sum it up: in the city, keep it off if ya want; on the highway, don't mess with it, the transmission has a mind of its own .
Just my $0.02.

 

You shouldn't ever have to push the O/D "Tow/Haul" button unless your towing a heavy load, and towing up grades. Otherwise just leave the O/D on, so that the light on the dash is NOT on. Otherwsie your likely to seriously hurt your fuel economy, especially at highway speeds.