Hello. I dont know why but rso completly removed oil from my map generation. It dont appear at all. I have many mods but tested without rso and everything was fine. I used

/c game.forces.player.chart(game.player.surface, {lefttop = {x = -2048, y = -2048}, rightbottom = {x = 2000, y = 2000}})

to uncover huge part of map and check on few different generation attempts. Tried regenerate command with "true" but that didnt changed anything. Help.

I will need zip with your mods and save file potentially.
It's possible you are unlucky unless there is no oil in starting area - then something went wrong and it's not spawning properly.
Please drop by forums and post thread with mods zip there.