1993 Cadillac DeVille Owner's Manual - Page 229

I A CAUTION: Snow can trap exhaust gases under your vehicle. This can cause deadly CO (carbon monoxide) gas to get inside. CO could overcome you and kill you. You can't see it orsmell it, so you might not know it isin your vehicle. Clear away snow from around thebase of your vehicle ,especially any that isblocking your exhaustpipe. And checkaround again from time to timeto be sure snow doesn't collect there. Open a window just a little on the sideof the vehicle that'saway from thewind. This will help keep CO out. I Run your engine only as long as you must. This saves fuel. When you run the engine, make it go a little faster than idle. That is, push the just accelerator slightly. Thisuses less fuel for the heat that get and it you keeps the battery charged. You will need awell-charged battery to restart the vehicle, and possibly for signaling later onwith your headlights. Let the heater run for awhile. Then, shut the engine off and close the window almost allthe way to preserve the heat. Start the engine again and repeat this only when you feel really uncomfortable fromthe cold. But do it as little as possible. Preserve the fuelas longas you can. To help keepwarm, you can getout of the vehicle and do some fairly vigorous exercises every half hour orso until help comes. 216