2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 112Get this manual
CHANGING THE COOLANT CAUTION:
Adding water instead of coolant lowers the antifreeze content of the coolantIf water is used instead of coolant, check, and if necessary, correct the antifreeze concentration of the coolantUse only distilled waterHowever, soft water may be used if distilled water is not availableIf coolant comes into contact with painted surfaces, immediately wash them with waterDo not mix different types of antifreeze
13.Install: Radiator cap