I'm not sure about the new anti-freeze but the old stuff such as Prestone will definetly gell in the cold if it is not mix with the proper water ratio. I've seen this many times when people use it straight out of the jug. Only in cold weather

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Ricali

03 C240 4matic wagon
95 300E 234,000
7 prior 240;s 5 still going
81 300sd gone
65 230sl gone
49 Studebaker Champion
90BMW convert.167,000
60 Dodge D-100