1999 Chevrolet Express Van Owner's Manual - Page 257

yellowblue Rear Axle When to Check and Change Lubricant Refer to the Maintenance Schedule to determine how often to check the lubricant and when to change it. See "Scheduled Maintenance Services" in the Index. Radiator Pressure Cap The radiator pressure cap must be tightly installed with the arrows on the cap lined up with the overflow tube on the radiator filler neck. How to Check Lubricant If the level is below the bottom of the filler plug hole, you'll need to add some lubricant. Add enough lubricant to raise the level to the bottom of the filler plug hole. NOTICE: Your radiator cap is a pressure-type cap and must be tightly installed to prevent coolant loss and possible engine damage from overheating. Be sure the arrows on the cap line up with the overflow tube on the radiator filler neck. Thermostat Engine coolant temperature is controlled by a thermostat in the engine cooling system. The thermostat stops the flow of coolant through the radiator until the coolant reaches a preset temperature. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See "Recommended Fluids and Lubricants" in the Index. When you replace your thermostat, an ACDelcoR thermostat is recommended. 6-21