1994 Chevrolet Suburban Owner's Manual - Page 280

Front Axle When to Check and Change Lubricant Refer to the Maintenance Scheduleto determine how often to check the lubricant and when to changeit. See "Scheduled Maintenance Services"in the Index. How to Check Lubricant If the level is below the bottom of the filler plug hole, you'll need to add some lubricant. If the differential is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the fillerplug hole. If the differential is cold, add enough lubricant to raise the level to 1/2 inch (12 mm) below the filler plug hole. What to use Refer to the Maintenance Scheduleto determine what kind of lubricant to use. See "Recommended Fluids and Lubricants" in the Index. Engine Coolant The following explains your cooling system and how to add coolant when it is low. If you have a problem with engine overheating,see "Engine Overheating" in the Index. The proper coolant for your vehicle will: Give freezing protection down to -20°F (-29"C), or -34°F (-37°C) in Canada and for vehicles with the cold climate option. Give boiling protection up to 258°F (125°C). Protect against rust and corrosion. Help keep the proper engine temperature. Let the warning lights and gages work as they should. 6-35