I just got hold of a new tester. First time I got 4 balls, ok figure you must be right, but then see air bubbles amoung the little cluster of balls, thump tester and two balls fall. One to bottom and other hangs in middle no matter what, so guess I have 2 1/2 balls. Still not adequate by far and no apology to walmart by me. You might want to go test one more time and thump tester couple times to see if all balls stay up. Air bubbles seem to stick to balls in new tester lot worse than old testers. I bought some prestone and am going to fill gallon jug one half full of walmart mix from radiator and add full strength prestone in small increments until I get appropriate reading. Proper level of antifreeze raises boiling point in summer same as it lowers freezing point in winter. Bugs me to leave something done halfassed.Farmer Brown said:DEFECTIVE TESTERS!!! I took my unused 9 gallons back in and traded for Prestone. While there we tested the W-Mart stuff I took back and it checked out OK. Sorry for bad mouthing W-M. They said the ball type will soak up antifreeze over the yrs and make them give weak reading. So---I buy a new tester, come home and all my stuff checks out fine.