Transmission Slipping in Cold Weather Until it Warms Up

I have a 2002 Chev Silverado 4X4, 5.3 engine with auto track. Purchased new with western snow plow, for my personal use only. Started about 6 weeks ago, 47,500 miles. I live I northern Wisconsin. We have had over 60 days of below zero weather so far this year.

The 1st time it happened it was 10 below, started my truck, put it in reverse it was slow to engage, this happened again a few days later. Didn’t think much about it. The next week, very cold, started truck put in reverse, wouldn’t move in reverse, if I gave it a little gas it sounded like it was slipping. After warming up 7-8 minutes, worked fine, pushed a little snow & even back dragged with no problem. transmission level was full.

Next week it did the same thing. In Oct 2007 right after I retired I had a complete transmission flush & filter change. Now 6 1/2 years later & 14,900 miles. It sits in the garage most of the time since my wife’s car get twice the mileage. I took it in & had it serviced, the same place I had it done at 33,571, complete transmission flush & filter. I asked the owner how it looked, he said normal. 3 days after that, very cold morning, went out started my truck, put it in reverse, wouldn’t move, step on the gas a little & again sound like slight slippage, let it warm up for 5 minutes, backed right up no problems, Drove all over town, took the wife shopping & had no problems.

As I said I plow just for my personal use, & I do have a transmission cooler which was installed on the truck when I bought it. Any idea what I may be looking forward to. Thanks for any information you might give me.

Frozen in Rhinelander, WI
Bud