A boot for a ball socket assembly in an automotive pivoting and/or rotating socket having a flange with one or more thinned sections or gates adjacent a point of attachment to a socket housing that provides an effective seal against contaminants when lubricant is not being added with external pressure and also flexes when exposed to internal pressure allowing contaminated lubricant to escape from the socket. A ring is embedded in the flange with inwardly directed teeth flanking the thinned sections or gates for securing the boot to the socket housing.