For most people, reading the dipstick can be kinda tricky. Did you take like 3 different readings when you saw the oil at the F? If not you may have skewed readings and you arent actually burning that much oil. Thats a TON of oil. Even with a Destroyed ringland thats ALOT of oil. I know for some people they jam the stick back in to hard and the o-ring on the stick causes pressure and gives them inaccurate readings.