I normally never use OD but I have used it on a trip to TN. Here in West Virginia there are allot of hills so I dont have many chances to use it. You should be able to use it on level ground but it your transmission begins to struggle or search for the right gear I would take it back out of OD. If you drive a Diesel it might be different but being a gasser I cant speak for that. I hope this helps.
What kind of tow vehicle do you have? What is the weight of your trailer? Bushhopper is right on with the do not use od if the trans is hunting or engine lugging. most manfactures recommend not using OD when towing.
I would install a trans temp gauge also. This will allow you to better decide to use it or not. If the temp starts going up around 250 â€“ 270, for diesel I donâ€™t know about gassers, then kick it off and ease up on the throttle.
I have a newer 5 speed that has the "Tow/haul" mode but am familiar with the OD as we had them when I worked for the county and towing with my father-in-laws '97 F-250.
Pa-n-law uses the gauge method and has over 125k miles on his truck with no tranny problems. He also is RELIGIOUS about changing the fluid and filter every 25 to 30k depending upon what he has been doing with the truck.
OddFinger, with that combination I would never attemp to tow in OD. I have towed in Od with a lot of my previous vehicles and never had a trans problem. If you have a feel for engine lugging, rpm, trans hunting it can be done with a lot of manual shifting but I don't recommend even trying with the v6 and the 3500 weight. (AJMO)
Just nodding in agreement. NO OD with the V6 and an automatic.
You may still look at the tranny temp gauge. It is cheaper than the repair bill and saved my first tow vehicle, Dodge Dakotaâ€™s (V8, auto) tranny.
After installing the gauge and checking with the local dealer service dept for the normal range, I hooked up my trailer and drove like I normally would. After climbing about half of a local 6% grade I looked at the gauge and was 35 degrees over recommended max. The engine wasn't lugging and no other signs of stress on the tranny. Manually kicked it down a gear and eased up on the go pedal and the temp started back down. Since then I climb hills more by the tranny temp gauge than what the truck can do.
High tranny temperature does not hurt the transmission per say, but it does (sometimes VERY quickly, like in 20 or 30 miles) degrade the fluid, and bad fluid is the cause of most tranny problems. If you haven't already, I would change the fluid, like yesterday...