at 90k i did 3 things as maintance on the 2011 crv new tires valve adjustment oil change with pup 5 -20 . last one was 5-30 castrol mangnatec i was getting about 19.5 mpg according to the computer before these things were done. now i get about 22.5 .3 mpg more. i am wondering which of these 3 things caused the mpg increase. or is it a combo of all three?