Tow/haul vs manual mode

[JasonH]

2017 Expy 6 Speed. If I'm pulling a light load (4700-5000) on fairly level terrain, I just let the trans do its thing. If I'm pulling a heavier load (6000- 6300) on slightly varied terrain, I will occasionally lock out 6th and it actually improves the mileage.

I've stopped using Tow Haul Mode in anything but flat terrain as it is programmed to use lower gears as an engine brake for hill descends, which I don't like. I manually select the desired gear while ascending a hill and use a higher trailer brake setting while descending.

I suggest locking out the top gear. When I was towing frequently I let the computer select gears. It would go into 6th and I had an OBD dongle so I watched the engine parameters while towing and could see it spooling the turbos. I thought it was so cool that it could tow my camper in the top gear by increasing boost instead of downshifting.

Then my manifold starting leaking. I attribute it to excessive heat from letting the engine spool the turbos for an extended period while towing. Let me tell you, it's not a cheap repair.