Originally Posted by Pick
The LB7 Duramax has a water cooled turbo, so the cool down period is not necessary. I am not sure if the LLY and LBZ are water cooled as they have the variable vane turbo.
I do a cooldown on my LB7 anyway after a major climb such as up Kimichi Mountain in eastern Oklahoma. We like to stop at the crest and enjoy the view for a while anyway.
Any other time, I figure that by the time I get the trailer parked, my LB7 turbo should be cooled enough.
I never do a cooldown when not towing or when towing on relatively flat terrrain.
I get 14-15 mpg towing my Classic 28 at 60-62 mph; even better when in a caravan rolling along at 55.