overdrive or 3??

[tyaquint]

i have heard different oppinions on this, but for normal driving and for highway driving, long trips, and also towing, when should you use overdrive or drive and when should you use 3?

t'

[TonyMazz]

Well I don't tow, but have a 4L60E tranny and I run OD (or it decides based on torque requirements) all the time.

I have never deliberately decided on using "3" for anything....

I have a stock truck and am getting 19-21.5 mpg so I am happy with it.

I also have a silverado duramax, and tow 6-10K lbs and typically, turn off the OD (have an allison tranny) when around town, and when I am on smooth highway with select the OD again.

With the allison you can select haul mode which changes the shift points too....

Can you tell us what you have in a vehicle, and what you tow in pounds etc.?

Think that would help us....

[Allbert]

Any time the transmission is shifting in and out of overdrive more often than I like (heavy loads, lots of hills), I'll pull it down into 3rd.

[tyaquint]

well i have a 98 BLazer 4x4 2 door 4.3 vortec.

not sure how much i tow just a 18 foot fiberglass open bow boat, and a steel trailer. its pretty heavy i forget how much though sorry

i usually just keep it in overdrive unless i am towing. not sure if thats the right thing to do

[TonyMazz]

Originally Posted by Allbert

Any time the transmission is shifting in and out of overdrive more often than I like (heavy loads, lots of hills), I'll pull it down into 3rd.

Yeah your comment reminds of something...I recall that some suburbans and mid-size SUV's would hammer their tranny's to death because they'd shift in-n-out of OD until it was gone....

That's why I bought the Allison with the option of shutting down the OD and interactively changing the shift points.

On the Blazer i.e. 4L60E I'd consider dropping down to 3 if you are pulling up a hill, and/or experiencing a shifting problem.

Quite frankly I wouldn't tow anything with a 4L60E / 4.3 I don't think they can stand it for long....Look up the GVW and we'd probably find something in the area of 6000 pounds so that'd be 4350 for the truck and the difference for the trailer...

Not much weight...maybe a snowmobile or bags of leaves or something...

[BlazerLT]

Keep it in overdrive unless it is constantly downsifting all the time.