I have a question that may be simple but I am not so sure. My new dodge truck takes Mid grade 89 octane gas according to my owners manual. However in my area many stations charge the same for mid grade and premium, about 1.58/gal. What I want to do is mix reg (87) with premium (93) to get a mid grade of 89-90. Normally I wouldnt worry about a few pennies but the difference between reg and mid grade is 22 cents/gal and my truck takes 36 gallons. Will mixing two grades give you a mid grade or is there something I am missing.