Did the Russians really get their fuel from the port of Vladivostok from the Americans in WWII ?

how they transported the oil from the Caucus oil fields? espeically after the Nazi attack and secruing the lower volga? were rail lines working very well between Vladi vostok and the Ural mountains and Moscow? which town or city in the Urals would the train have stopped to give fuel for the factories there? and why Hitler and the nazis thought they could disrupt the russian oil supply by taking the oil fields in the caucus mountains?