I misinterpreted the way this feature works. I thought it was more of an AWD feature. No. I just read a better written description from GMC and they're calling it Auto 4 Hi. They say it's fine for any driving condition but will cause wear faster to 4x4 driveline. I have 35k and I'd say possibly half that was on Auto 4x4. Either on the highway or riding through potholes at average 30 MPH. What can I say for what I've done to the truck? About to do the first transmission and differential service. I use the severe chart as I'm in New York City and Long Isiand.