A transmission having a pressure controlled vent system, including a vent tube configured to engage a transmission such that a first opening of the vent tube is in fluid communication with an upper portion of a transmission cavity, a second end defining a second opening configured to be in fluid communication with an external atmosphere, and a bifurcated portion between the first end and the second end. The bifurcated portion includes a first tube segment and a second tube segment in parallel with the first tube segment. A pressure relief valve disposed in-line within the first tube segment and a vacuum relief valve disposed in-line within the second tube segment. The pressure relief valve cooperates with the vacuum relief valve to maintain a predetermined range of pressure differential between the first opening and the second opening. The vent tube may also include a moisture and/or a transmission fluid separator.