Well then its doubtful its the FF Then. Someone probably did a drain and fill and used concentrate. Possibly they just replaced a bad overflow tank and filled it with concentrate.
'99 Ford Taurus 145k (Vulcan v6) - Current Fill = M1 HM 5w30 | FL400S
'02 Buick Century 98k (3.1 v6)- PU 5w30 / Fram Ultra XG 3980 / Filter mag