What is the most efficient way to boost oil storage? I am striving for the moon mission which requires 45k oil. I'm at 41998 storage with 27 oil wells and the steel cost is growing extremely quickly. I've considered tankers as well but at 1250 alloy each that seems prohibitively expensive as well. Is there an angle I'm missing?
Oil Wells and Tankers are the only way to increase Oil Storage before you can construct a Moon Base (after Moon Mission, and requires Unobtainium)
In theory you could reset, and try again with a higher paragon bonus, but at this point it's probably worth continuing to Unobtainium Huts.
The best tactic I've found is to maximize my crafting bonus, making sure I have as many workshops and factories as possible, and make tankers then. If you can get up to 5 or so Tankers for the 1250 Alloy, it becomes a pretty strong investment. It also isn't subject to the Price Ratio, so it's just as effective to buy your 50th Tanker as it is your 1st.
I made a spreadsheet about this.
The cost-efficiency of oil wells and tankers are both affected by your crafting ratio, but tankers are affected a lot more-both due to the higher number of tankers per craft, and because the ingredients for tankers get crafted more times than the ingredients for wells, so the ratio is applied more times. I'm assuming you only care about the steel cost, since both require scaffolds, and alloy doesn't take that much titanium, so the best measure of cost efficiency is oil capacity per steel.
The useful answer: if your craft ratio is between 5.14 and 5.68, oil well 32 is a better deal than crafting tankers. After 32, tankers are the better option. If your ratio is lower, oil wells remain the better deal a little longer, and the opposite if your ratio is above 5.68.