WI: The Germans aim for Stalingrad in 1941

[American]

Okay, I haven't really seen anyone pose a question on this what if so here goes:

What if in Operation Barbarossa it was planned to capture Stalingrad and the oilfields on June 1941? I am aware that resistance in the southern part of the front was especially fierce, but could the Germans hold a defensive line on the North/South part of the front while going forward in the south?

Now please inform if I am missing on any details as I am unaware of the defenses for Stalingrad or the Caucasus in 1941, but if they were close to grabbing Stalingrad and and the Caucasus oil fields in 1942, when they lost a good portion of their invading strength, faced a less mobilized army, and no longer had the surprise effect, could the occupation of the south russian front knock them out of the war, or at least temporarily, but severely, stall to mount subsequent offensives with ease?

This could happen but the Soviet Union is large and stalin is stubborn. So stalkn would eventually find more oil in other parts of the country. He would keep Russia in the war until everybody was dead. So no the Soviet Union would not surrender right then and there