1997 GMC Suburban Owner's Manual - Page 308

If the differential is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the filler plug hole. A 50/50 mixture of water and the proper coolant for your vehicle will: Give freezing protection down to -34°F (-37°C). Give boiling protection up to 265 "F (129 "C). Protect against rust and corrosion. Help keep the proper engine temperature. Let the warning gages work as they should. If the differential is cold, add enough lubricant to raise the level to 1/2 inch (1 2 mm) below the filler plug hole. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See "Recommended Fluids and Lubricants" in the Index. Engine Coolant The cooling system in your vehicle is filled with new DEX-COOL@engine coolant. This coolant is designed to remain in your vehicle for 5 years or 150,000 miles (240 000 km), whichever occurs first, if you add only DEX-COOL@extended life 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. NOTICE: When adding coolant, it important that you use is only DEX-COOL@ (silicate-free) coolant. If coolant other than DEX-COOL@added to is the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolantwill require change sooner at 30,000 miles (50 000 km) or 24 months, whichever occursfirst. Damage causedby the use of coolant other than DEX-COOL@ is not covered by your new vehicle warranty. -- 6-26