I was wondering what effects if any it would have on my truck by driving my 2001 5.2L 4x4 with the O/D shut off..?? Thanks

 

Around town, just turn it off.
Also turn it off if you have lots of hills or oversize tires.

I have found that if you turn it off with hills, your gas mileage goes up a little bit.

 

Thanks for the reply, I have a five mile stretch to work that is 55 MPH(with a hill or two). Should I turn it on for this, or not worry about it ?

 

the damage that can happen while using o'd, if any, is that your truck will 'search' for gears when the engine is loaded.. this generates heat... heat munches on transmissions like a 30 year sorority reunion does pastries.. not good..

it seems counter intuitive, but running a higher RPM for the same speed (lower gear), often takes the load off of an engine and runs it in an area where it's not sucking excessive air/fuel which it's not burning.. it keeps it comfortably holding a steady engine speed and forward speed, if you will.. this actually conserves fuel, and makes life much easier on your transmission.

use o/d if your truck isn't struggling to maintain speed.. use o/d if your truck isn't hunting for gears... DON'T use o/d if your pulling or hauling a significant load, or in situations where your truck is shifting a lot..

kinnit?

 

engine rpm will be slightly higher but your ability to pull a hill without that lugging feel will improve. at moderate speed, say up to 60, the rpm increase will be an insignificant amount. above 60 your rpm's would be a bit high and you'll get worse gas mileage.

i turn OD off when my speed is in the 45-55 range, and turn it on when i can stay over 55.

the power band of our engines seems to be somewhere in the 1800+ rpm range. 1500-1600 is a little luggy feeling and it struggles up hills. 3.55 gears and bigger tires contribute to this feeling.

 

Thanks guys...much appreciated. I drove around today with the O/D off, it is like a different truck.

 

I agree with everyone's responses. I never use od in city driving, to much up and down shifting...Extra wear and heat, Plus in od at low speeds the load on the engine won't let the converter lock up...more heat. I only use od on the highway and am close the 200k on my original trans! I do have a shift kit in it to which helps, quicker shifts means less slipping, heat and wear.

 

PITA part is you have to remember to turn it off every time you start the truck. At least on my 01 its that way

 

I had better gas mileage towing/hauling 3500 lbs WITHOUT OD than WITH OD. This was over a 800 mile trip when i moved to Indiana.

Plus the truck drove better.

It is actually better to throw OD off unless you are over 50-55. City driving will suck gas no matter what you do. They are just big heavy trucks with low gearing!!!