Don't warmup up your car-R&T

I was with a guy once who shut his truck off for about 5 hours and the temp outside was -15. There was 5 of us driving trucks going to the same destination. When we went into the truck stop all but him let their trucks idle. When we all left he just started his truck up and tried to keep up with us and that COLD motor bent every push rod in the engine.... The Cat. tech where he had to take the truck to told him never just start a motor up in this weather and go, let it warm up !!