What Mesora123 stated is totaly untrue. The fact is Maran Reb Moshe z”l himself never ate chalav Stam ever. When he first arrived in America, with chalav Yisroel not being pre-packaged available, his cousin, Rav Hertzel Kantrowitz z”l, would go to a farm every 3 months, watch the milking and bring to R’ Moshe a container of chalav yisroel. This was the only that he would drink. For hid family and yeshiva was a different story. However, for himself, R’ Moshe would consistantly go for years for 3 months at a time without tasting milchigs. (Not that easy). Until after the war, with the influx of chasidim among the survivors, who made chalav Yisroel readily available.