1998 GMC Savana Van Owner's Manual - Page 190

Snow can trap exhaust gases under your vehicle. This can cause deadly (carbon monoxide) gas CO to get inside. CO could overcomeyou and kill you. You can't see it smell it, so you might not or know it is in your vehicle. Clear away snow from of around the base your vehicle, especially any that is blocking your exhaustpipe. And check around againfrom time to time to sure snow be doesn't collect there. of Open a window just a little on the side the vehicle that's away from the wind. This will help keep CO out. Run your engine only as long as you must. This saves fuel. When you run the engine, make it go a little faster than just idle. That is, pushthe accelerator slightly. This uses less fuel for the heat thatyou get and it keeps the battery (or batteries) charged. You will need a well-charged battery (or batteries)to restart the vehicle, and possibly for signaling later on with your headlamps. Let the heaterrun for a while. If you have a diesel engine, you may have to run it at a higher speed to get enough heat.Then, shut the engine off and close the window almost all the way to preserve the heat. Start theengine again and repeat this only when you feel really uncomfortable from the cold. But do it as little as possible. Preserve the fuel as long as you can. To help keep warm, you can get out of the vehicle and do some fairly vigorous exercises every half hour or so until help comes. 4-26