2009 Mercury Sable Owner's Manual - Page 280

Maintenance and Specifications If you drive in extremely hot climates: • It is still necessary to maintain the coolant concentration above 40%. • NEVER decrease the coolant concentration below 40%. • Decreased engine coolant concentrations below 40% will decrease the corrosion protection characteristics of the engine coolant and may cause engine damage. • Decreased engine coolant concentrations below 40% will decrease the freeze protection characteristics of the engine coolant and may cause engine damage. • Refer to the chart on the coolant container to ensure the coolant concentration in your vehicle will provide adequate protection at the temperatures in which you drive. Vehicles driven year-round in non-extreme climates should use a 50/50 mixture of engine coolant and distilled water for optimum cooling system and engine protection. What you should know about fail-safe cooling If the engine coolant supply is depleted, this feature allows the vehicle to be driven temporarily before incremental component damage is incurred. The "fail-safe" distance depends on ambient temperatures, vehicle load and terrain. How fail-safe cooling works If the engine begins to overheat: • The engine coolant temperature gauge will move to the red (hot) area. • The service engine soon indicator will illuminate. If the engine reaches a preset over-temperature condition, the engine will automatically switch to alternating cylinder operation. Each disabled cylinder acts as an air pump and cools the engine. When this occurs the vehicle will still operate. However: • The engine power will be limited. • The air conditioning system will be disabled. Continued operation will increase the engine temperature and the engine will completely shut down, causing steering and braking effort to increase. 280 2009 Sable (mgo) Owners Guide, 2nd Printing USA (fus)