1995 GMC Yukon Owner's Manual - Page 90

How long should you keep the coolant heater plugged in'? The answer depends on the weather, the kind of oil you have, and some other things. Follow this chart. Viscosity/ Oil Grade SAE 1 ow-30 SAE 15W-40 32°F to 0°F (0°C to -18°C) Not Required Not Required 0°F to -10°F (-18°C to -23 " C) Two Hours:;: Two Hours:': Below -10°F Below -23" C Eight Hours": or Overnight Eight Hours* or Overnight $:The times listed are minimum times. It wi 11 not harm either the coolant heater or the vehicle to leave the coolant heater plugged in longer than the times stated. See "Diesel Fuel Requirements and Fuel System" i n the Index for information on what fuel to use in cold weather. lf Your Diesel Engine Won'tStart If you've run out of fuel, look at "Running Out of Fuel" (see "Diesel Fuel Requirements and Fuel System" i n the Index). If you're not out of fuel, and your engine won't start, do this: Turn your ignition key to RUN. Make sure that the GLOW PLUGS light is out. Then IMMEDIATELY turn the ignition key to START. If the light doesn't go off, wait a few seconds, then try starting your engine again. And, see your dealer as soon as you can for a starting system check. If the light comes on and then goes off and you know your batteries are charged, but your engine still won't start, your vehicle needs service. If the light does not come on when the engine is cold, your vehicle needs service. If your batteries don't have enough charge to start your engine, see "Battery'?in the Index. Be sure you have the right oil for your engine, and that you've changedthe oil at the proper times. If you use the wrong oil, your engine may be harder to start. If the engine starts, runs a short time, then stops, your vehicle needs service. 2-18