Overdrive

[neemaghannadi]

I know there have been many posts regarding this in the past, but there hasn't been a clear answer. I live in a very hilly area and I dont know if I should keep overdrive off or on while going downhill or uphill. Can you guys answer that for me? Thanks

 

[Tim K]

Well, I am no expert...but I keep OD off unless I am on the highway or driving over 50mph for extended periods. Leaving OD on in conditions where you vary speeds above and below the 40-50mph range makes the trans flip flop back and forth from 4th to 5th. This can't be good for the engine/trans. Also, when going up hills your trans tends to downshift to 4th anyway for the extra power and torque, so why not keep it in 4th to begin with. Plus, when going down hills, keeping it in 4th allows the engine to slow the truck down rather than working your breaks. If you've ever driven down a mountain they always advise you to drive in lower gears as opposed to using the breaks. Using the breaks alot to slow you on hills not only wears more on the breaks, but can easily overheat them.

So in my non-expert opinion....keep OD off unless you are doing highway or consistent higher speed driving.

 

[Stephen]

I've always left it on unless I'm going down a highway grade, and then I first turn O/D off, then drop to 2 of thats not enough to keep the speed constant. Its best for fuel economy to leave it on, and I figure if it were meant to be left off the button would activate overdrive not deactivate it.

 

[01EB5.0]

I almost never shut mine off either. i do a lot of driving and usually it's out on back roads (55 or over) so for me it's not good in terms of gas milage to shut it off. if you notice it shifting a lot at the speed your cruising at, then maybe you could shut it off, but it's made to be on so just leave it. My old transmission lasted 91,000 miles (most of which included towing a heavy trailer) and my O/D module was not what wore out, in case you were thinking that might be a problem.

 

[Milo]

I think that you will find most owners manuals recommend keeping it in the default ON setting at all times other than hills, trailering etc. I have owned several vehicles with this feature and never had a problem. It was "on" 99.99% of the time.

As Steven stated, the default is ON. Otherwise not only would it be inconvenient to turn it off every time you drove the vehicle, but most drivers would forget to disengage it all the time.

 

[Robert]

As an experiment a few weeks ago, I drove one complete tank of gas with the OD off. The only time I turned it on was on the part of my daily commute where I am on the highway for about 5 or 6 miles at 70 MPH. My mileage on that tank was about 2 1/2 mpg less than the several tanks before and the several tanks after.