2007 Suburban

[Brian Vinson]

When Driving through the Mountains with 5 Adult passengers should i use the tow and haul button?

[MikeNH]

If the transmission is shifting too much, I would use it. If it is able to hold gears then I would not bother.

[Colossus]

If you are driving thru REAL mountains like here in Colorado, yes, use it.  If you are driving thru the hills that you people have back east, then you probably don't need it but try it anyway. 

[5proms]

Instead of the tow/haul button, I would manually shift to a lower gear that keeps the engine higher in the torque curve which would mean less shifting.  I'm assuming you have the 5.3?  Shift to a gear that keeps your RPM around 2000-2400 rpm, that minimizes shifting in your tranny, which keeps the transmission heat lower.  Fuel economy will be a little less, but what's a few cents worth of fuel relative to the long life of the tranny.  

 

I'm at 230K on my '05 Yukon XL, original engine and 4L80E transmission.  When I tow, it's always in 3 with tow/haul engaged.