Actually that 7% represents "loss rate of matériel", shipping losses were 7.8% eastbound, 3.8% westbound. The convoys were only suspended because escorts were redeployed to a) support the Malta relief efforts and b) TORCH. In the interim, Tovey, CiC Home Fleet had restructured the escort forces, providing "FDE" Fighting Destroyer Escort i.e. 12-15 destroyers, with an Escort Carrier, Coastal Command forces on Soviet soil etc. and coordinating running e/b & w/b sharing escorts,meeting in the Barents Sea. While there were shipping losses, when fought through with these escort forces KM U-Boat and Luftwaffe losses soon became prohibitive. Incidentally, the US tankers loaded with 100-octane aviation fuel were sent by this route after the Japanese had complained of fuel sent to the Soviets via Vladivostok. The Soviets had been buying and shipping from California to supply the Soviet East long before Barbarossa; it was cheaper than shipping oil from Baku et. al. via the Trans-Siberian RR. There’s a lot here already re: Soviet oil, but Soviet coal resource loss to the Germans was more severe than oil, in fact the Soviets did well as far as oil goes. In terms of material required for industry, German forces occupied an area that contained 60% of the USSR’s armament industry,74% of its coke, 63% of its coal, 71% of its iron ore, 68% of its pig iron, 60%of its aluminium, 58% of its crude steel, 57% of its rolled steel output, and 42% of its electrical generating capacity. Prior to the German onslaught, the Soviets had utilized mineral resources closer to the western industrialized regions because it was cheaper to transport, and they were required to do a lot of R&D of new mineral sources when those sites fell into German hands. For example, when the manganese mines in the Nikopol were overrun, the miners were evacuated to another mine site in the Northern Urals, which required a great deal of expansion. In Kazukstan and Uzbeckistan the production of vanadium, wolframite(tungsten), and molybdenum was greatly increased to compensate for the loss of mines in the German occupied zone. Production of aluminium was begun anew near Sverdlovsk and the Kuzbass Basin. So what if the Germans seized Baku? They’d mismanage it, just like they did with all their gains, the transportation problem was never even close to being solved, it could always wait. The Germans simply operated hand-to-mouth, or rapaciously, waiting for the war to end until they could reorganize everything; they did much the same thing in most of Occupied Europe. Remember, the Germans win only if they can seize the oil bearing areas, get them producing again AND get the oil back to Germany to fuel German industry. And all this before before the US feeds, arms and fuels the rest of the world to defeat Germany. It's a no win for Hitler. One last thing, much of the oil production equipment the German “Oil Brigades” took with them from Breslau to Maikop was Russian (it took weeks to get there, German transport, logistics etc. were brutal). The Germans had produced it in 1940 at the request of Stalin etc., 100 odd derricks, pipe, pumps etc. in exchange for Soviet oil, all part of the German-Soviet trade provisos of the non-aggression pact. It was never delivered by the Germans, but the US would make up for it. Incidentally, that "Blood for Oil:" link posted, is clearly based on "Oil and War" by Goralski & Freeburg. I recognize it - almost verbatim in areas, even going so far as structure and quotes! It’s decent enough, not great; the authors are/were journalists, not scholars or historians, the book dates back to the late 80's,i.e. before Soviet records became more accessible, and it’s not without errors, just an FYI.