I am changing oil and filter every 7500mi or 1 full year

per mobil website, oil will be just fine within 5 years in container as only cap tight. per user group discussions, one year inside engine oil will not have negative impact to engine.

some users change full syn oil at 10kmi intervals, some even go for 15kmi, but i'll stay with 7500mi to be safe. i am thinking to do an oil analysis after 7500mi...

the cheapest mobil syn oil is in walmart.