Don't need the oil to do it, just ~5 hours or so at the end. Right now, due to the bot land, I expect it'd be trivially easy for a techer to rush to 10k A, stock, switch to TMBR, and get over $30m NW. If you can manage 250 A per hit, which doesn't seem entirely unreasonable, you're looking at only about 300 turns spent getting BPT, land, and buildings.