For me and after trying a bunch of different ways for oil seems the best outcome anyway on my game is what I have.
Allies really had no problem getting oil. UK after 1940 when Persia area fell they got most of there oil from Venezuela. But UK did get Iran back with Russia based on both attacked together in 41 in separate territorial attacks. They didn’t like each other at the time. On my map history wise Russia controls northern half of Iran and UK southern half of Iran.
Yes I can see oil shipment boats from refineries could be hit by axis in the Atlantic. I did test in game if a enemy sub was in a sea zone touching a territory with an oil refinery you could convoy attack it. You would lose I believe a flat rate of 3 icps from your income representing oil transport ships being sunk. Now you could play remove right away 3 icps from your income or wait and see if allies try to kill the sub before the penalty kicks in at end of your turn. Also the refinery could be SBR up to 3 damage.
I think this type of raiding was stopped because we went to oil derricks. It got to strong in certain areas like UK and Dutch islands and depleted Japans income to much. Just more ideas here. And also there’s enough convoy boxes on map to include oil basically.
Like G40 map the convoy boxes should be a bit further out in the Atlantic.
My opinion is the to keep it simple and have the oil mostly more important in game for the Axis at key locations based on the oil producing chart in war. It would be great if UK didn’t destroy there oil wells in Burma when Japan started to invade. This would help Japan get another bonus point if controlled. Probably with so much fighting there they Japan didn’t have the option probably to repair them wells.
But funny thing is they brought engineers or repair men from Japan and used the captured workers on Sumatra and Borneo to help rebuild them oil wells that UK/FEC destroyed when Japan attacked in Dec 41 and a bit later.
Not a big fan of pentalizing a group of units whether ground, navy or planes. It can affect the game more on this scale level. I like it best in smaller version games like Barbarossa where only a small fraction are affected based on more territories in them game maps.
OK had my say so I’ll chill out now. lol