A by-pass valve capable of activating at least two different temperatures is disclosed. The valve has a valve chamber housing a valve mechanism having a piston-cylinder arrangement. The cylinder defines two separate chambers therein for housing two different thermal materials each having a different activation temperature. A piston is arranged in each end of the cylinder operably coupled to the corresponding thermal material housed within the cylinder. A valve spool or valve sleeve is operably coupled to one of the pistons associated with the valve mechanism, the valve spool or sleeve adapted for sliding within the valve chamber for controlling flow to the fluid outlet ports formed in the valve. In some embodiments, the valve mechanism housing two different thermal materials can be arranged in combination with additional valve mechanism housing different thermal materials allowing for further multi-stage activation allowing for various flow arrangements through the valve.