How are you achieving E30 (or E50 for CPI users)? I would like to hear from those who are actively calculating what they’re putting in the tank, which would mean you’ve tested the content in some fashion. I typically run E30 (E85 and 93) mix. I tested the E85 at a local station, and it was E85. I used to use an app to calculate how much I needed based on the tank size (15.9 gallons) to achieve E30. Little did I know the calculator was flawed, and I was running something closer to E35. Now I use the Fuel-It Ethanol sensor. With the Fuel-It app, you enter the tank size, as a whole number (16), and it’s capable of spitting out how much ethanol and gasoline is needed to achieve a specific blend. However, it’s also incorrect. At 1/8 of E30, I decided to fill up. I open the app and calculate how much it claims I need to maintain E30. 9.1 gallons of gas and 5.2 gallons of E85. Now, I’ve been using the Fuel-It sensor since late July/early August, so I know the numbers above are incorrect. I’ve gotten pretty good at being able to calculate the difference too. So I add 4.1 gallons of E85, which measured as E85. That brought my ethanol content up to E61. I then added 10.5 gallons of 93, which contains up to E10, and once things settled down, I achieved my target mix of E30. Why the discrepancy? There are several factors. One is simply that the applications can’t possibly take into account just how much fuel is left in the tank. The fuel gauges themselves are analog. As fuel sloshes, the level changes, and there’s always some fuel left even when you try to run it all the way to empty. I suppose this is my argument for getting the ethanol sensor. You’d know what’s going to the fuel pump, and it’ll appear in your logs.