To D or to OD, that is the question...

[shaman683]

Hello,

I am still getting used to my "new" '96 Chevy S10 I recently bought.

I'm no spring chicken, but this is my first truck, and I have a question...

To commute to work, I drive 17 miles daily(both ways) on a state highway over moderate hills and "hollers" here in the Missouri Ozarks.

I encounter a couple of steep hills, but it is flat to gently rolling terrain for most of my drive.

Here is my question: Should Drive in "D" or D with the circle around it for best fuel milage and less wear and tear on the engine?

Thanks for your help!


Best regards,
-Skip

[greasemonkey]

Generally I don't use overdrive. You get about the same gas mileage anyways. You mentioned some steep hills in you post. Running in overdrive while going down a steep grade is hard on the tranny and going up a steep grade brings you out of your engine's powerband and leaves you going very slow up the hill. I'd stick with "D", no matter what gear your in, the engine will get the same gas mileage. Id' also change the gear oil on a regular basis.

Jim
"the greasemonkey"

[mrjohnwayne]

ah but that is the beauty of an automatic. If most of the drive is fairly flat leave it in OD. going up any kind of decent incline will knock it down into 3rd (D) on its own.

[greasemonkey]

Is the truck auto or manual?

Jim
"the greasemonkey"

[75K30]

proper rear axle selection is key. Finding a ratio that allows the use of overdrive is the most desired.
Allowing an auto transmission to engage overdrive and the converter to "lock-up" is essential for the transmission to cool properly. A converter that is in "lock-up" is mechanically coupled and does not slip. Slippage causes heat, and heat kills.
If a transmission can't run in overdrive, and is not permitted to run in overdrive, and the converter is unable to lock up, it will not last a very long time.
A vehicle with the right axle ratio that is permitted to run in overdrive, will get better mileage than one that has the wrong ratio, and the transmission will last longer. This is one of theose cases where a lower ratio may be better.
I am not suggesting to run right out and change the axle ratio, but if the vehicle is being weighed down by any trailers, campers, or larger tires, it might be a good option.
A stock vehicle with stock tires should pull a decent grade in overdrive, with little effort, and should be allowed to.

[waterloo88chev]

OD just gives you that extra boost you need to make it up inclines, pass people, etc, id defenitely use OD, quite obviously unless youre pulling... but other than that i always use it

[greasemonkey]

Overdrive is just an overall higher gear. It would not help in going up an incline, as this would leave you going very slow and put uneeded strain on the engine.
Overdrive can refer to two different things. An overdrive is a device which was commonly used on rear-wheel drive automobiles to allow the choice of an extra-high overall gear ratio for high speed cruising, thus saving fuel, at the cost of less torque. It also refers to a combination of gearing inside a transmission or transaxle which results in the output speed being greater than the input speed. In the latter case, "overdrive" does not refer to a physically separate identifiable part/assembly.

Jim
"the greasemonkey"

[shaman683]

Greasemonkey, my truck has an automatic transmission.

[scottie]

overdrive means that you output is turning faster than the input in the tranny. without a doubt, always keep it in OD unless your towing or 4wheelin. not being in OD is the same as driving a manual on the highway and never shifting to 5th. you have overdrive, use it!