Does the engine really have a sensor? BMW used a time on engine formula for as long as I knew. Hours of on engine time and miles on the odo to compute time for oil change. I bet the Honda ECU does the same, so synthethic or conventional will run the same intervals. This way hours spent idle in city traffic still go toward the oil change interval not just miles on the engine.

I'd run synthetic for the fuel economy alone. I'd also use the maint. minder on the dash for the oil changes, it will save you the most money per oil change. And is likely still a conservative number so you still should have relatively clean oil at the change time.

My company car has an oil minder, but as far as I can tell it's based on milage alone, boo! Way to cheap out Ford