At 5,000 miles, I am averaging 23 with mixed driving and a few sprints here and there (to keep the carbon out of the cylinders....ha!). Best mpg was 24...worst 21.....oil was changed at 3,000 miles and dealer put dinosaur 10w-30 in.....ouch!...thinking of switching to full synth 5w-30....have heard mpg may increase 2 mpg...any thoughts?