well i wouldn't use synthetic until the car had at least 10,000 miles, just because you want to make sure it's broken in properly. furthermore, i would do the first oil change EXACTLY on schedule, not early, because they might be using some kind of special additive with the oil to help accomodate break-in. i don't know, so i figure i better just stick to the schedule. as far as hondas running better on non-synth, couldn't tell ya. my accord and gsr both definitely like the synthetic better.