1998 Buick LeSabre Owner's Manual - Page 271

NOTICE: When adding coolant, it is important thatyou use onlyDEX-COOL@(silicate-free) coolant. If coolant other thanDEX-COOL is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner at 30,000 miles (50 000 km) or 24 months, whichever occurs first.Damage caused by the use of coolant other than DEX-COOL@is not covered by your new vehiclewarranty. What to Use Use a mixture one-half clean water (preferably of DEX-COOL' coolant which distilled) and one-half parts. you use this mixture, won't damage aluminum you don't need to add anything else. . I f -- I ' Adding only plain water to yourcooling system , can be dangerous. Plain water, or some other liquid like alcohol, can boil before the proper coolant mixture will. Your vehicle's coolant warning system isset for the proper coolant mixture. With plain wateror thewrong mixture, your engine could get too butyou wouldn't hot get the overheat warning. Your engine could catch fireand you or otherscould be burned. Use a 50/50 mixture of clean water and DEX-COOL@coolant. 6-21