I have a 21' toy hauler that I estimate to weigh about 6k loaded. The question is: is it ok to tow on relatively flat ground with the tranny in OD?

Well is your tranny stock or built at all? Also has it been rebuilt and if so how long ago? I wouldnt personally if it was stock.-Jordan-

Yes, it was just rebuilt (stock). Has about 8 hours on it.

I have a 21' toy hauler that I estimate to weigh about 6k loaded. The question is: is it ok to tow on relatively flat ground with the tranny in OD?

I would base that on trans temp and ablity to hold the gear without slippage. Like myself I've got a manual but normally don't tow any faster than 55-60 MPH being my trailer tires are rated only to 65 MPH. So I can pull 5th gear most of the time on flat ground. But as soon as the speed falls below 50-53 MPH I drop from 5th to 4th to reduce strain on the trans and 5th gear nut. So the same should be true for Auto's as well. As your speed starts to slide down you know when to kick out of OD and pull your RPM's up to lighten the load.

Thank you. That's what I did this past weekend. When I could hear that the motor wasn't straining and the Tranny temps were low (~150), I would turn on the OD, but as soon as I felt or saw a substancial incline coming up, I would turn it off. With diesel getting so costly, everything I can do to conserve helps.

Automatic trannies will tell you your doing something wrong by either slipping or by gaining temperature. So if the tranny temp is low and the gear is holding strong then enjoy... The best man to talk to about auto's and towing heavy is CajFlynn that man hauls the loads and does it for at least million of miles!

My built tranny dopped temps when in OD. triple lock as well so no slippage. Another thing if you have an egt, as engine speed drops the egts will go up. I normally kick the od off when engine speed drops to about 1600rpm.

having towed with a stock auto and a built auto, a stock auto i would tow in OD, for you 6K is nothing and OD won't be a problem, but for you the key is to keep the rpm's above 1,600, because you will loose your line pressure below that.Another issue is modifications, regardless of how new your stock auto is you will burn up the OD pack with anything over 40-60hp stock, because there is not enough line pressure to put the pressure to the clutch pack.A built auto(like my DTT), i just got back from hauling a 14,000lbs 5th wheel camper to Virginia and its a night and day difference. But a built auto will handle the weight in OD while my stock trans wouldn't, she would slip eventuallyu from 1,400(when it goes in), all the way to 1,800rpm's, so eventually you should keep the rpm's up via locking the O/D off. Another thing to consider is your stock auto has a single disk, which shouldn't be lugged around in low rpm operation(below 1,600rpm). The single disk that dodge gives you doesn't have a billeted front cover, so expect wear onto it.My advice for longevity and being that its so new is to buy a good triple disk(or a good billet single if your hauling under 10,000lbs, and have no modifications), and a good hauling valve body from Goerend DTT etic.If you do that you new stock trans will most likely outlive the truck.