I go by what the maintenace minder on my HCH2 tells me to do. My first oil and tire rotation was done at 15400 kil with 5% still to go. No filter on the first change! "Yes I know the filter should be change", but I am going to do as I'm told. The car uses 0-20 Honda brand oil. [Not sure if it is sinthetic or not] I change oil and filter in my MX5 every 3000 kil. and have been for years. What a waste! The only reason I post this is maybe we change our oil more than what is required. Most people using Mobile-1 0-20 should be able to go a year before changing regardless of distance traveled? For what its worth, H