How could you get Turkey on the side of the Axis, I'd like a little more detail than just "have a divisive government that allows for a pro-axis leader", please do go into details as to who could lead this pro-Axis Turkey and when & how they could gain power? - Or at the very least a Turkey which is anti-Soviet Union and that would join Germany in a war against them.
What would the effects of this be? With a nation that directly borders the Caucasus and thus it's oil how could this affect the Axis advance into the Soviet Union? Would we see Moscow fall rapidly with a Germany that's got oil from an ally that's invaded the Soviet Union from the south? How far could Turkey get, would it be stopped at the Caucasus mountains, or could they dig deeper into the Soviet Union?
Also what would be the affects on the Middle East and North-East Africa with another Axis member that's powerful, got a good and strong army and right next door rather than across a sea.