towing: O/D off with aux trans cooler?

[rgk]

I have heard you should turn off your overdrive when towing a trailer. I have a trailer weighing roughly 1,500 lbs, as well as an auxiliary transmission cooler installed in-line with my stock radiator trans cooler. Should I still turn overdrive off when towing, or does the aux cooler make it OK to leave it on?

[atraudes]

The goal of turning overdrive off when towing or going up mountains is to keep the transmission cool, so assuming you have a quality cooler like the recommended B&M 13,000 BTU (which I think you do), you should be fine. Unfortunately I don't have personal experience so I can't say for sure.

Regardless, it would be prudent to install a transmission temp gauge; maybe just a temporary one for the time being so you can keep an eye on things.

[patqx4]

Personally I wouldn't bother at 1500lbs, that's not a lot of weight for these trucks, especially with an additional cooler. The 3.5 with auto is rated for 5000lbs. However if you're concerned about it, it certainly wouldn't hurt..