TM10-3930-660-20 7-10. COOLANT OVERFLOW TANK - REPLACE (Cont’d) 2. FILL COOLANT OVERFLOW TANK (1). A 50-50 mixture of ethylene glycol and clean water is used in the 6KVRRTFL. Use of plain water coolant is not recommended. Never add coolant without first a. b. c. d. e. f. diluting to a 50-50 mixture. Open overflow tank cap (6). Add two quarts of coolant to overflow  tank  (1). Close overflow tank cap (6). Slowly remove radiator cap (7) and allow pressure to escape. Add coolant to radiator (8) as necessary, until coolant level reaches bottom of filler neck. Install radiator cap (7). 7-27