A milling cutter, having an adjustable cooling mechanism, has a tool body having a body central bore. At least one flute is formed on a body peripheral face. Each flute comprises a first row of insert pockets and at least a second row of insert pockets axially rearwardly displaced from the first row. The cooling mechanism includes a center pin having at least two grooves axially spaced apart from one another along the length of the center pin. A relocatable seal is seated in one of the grooves. When the relocatable seal is seated in a first groove, the body central bore is in fluid communication with cooling holes associated with a first number of rows of inserts; when the relocatable seal is seated in a second groove, the body central bore is in fluid communication with cooling holes associated with a second number of rows of inserts.