The oil cans are glitched so no matter how long I wait they don't fill all the way. Paying for the premium version doesn't add much but gives you a bonus when you sell Still have to watch ads for everything. Honestly the 1st oil station you start out with makes the most oil and money and is much cheaper to upgrade. Makes 75Mil oil while my most expensive one makes 10M. Most expensive upgrade currently for the 1st oil station is 200M dollars and the cheapest for the best one is 1B dollars.