I agree, a 3 mile commute probably isn't the best for the engine. It doesn't cost $150-300 to change the oil, maybe if you go to the dealer. You can buy the special diesel Shell oil at Wal-Mart. Looking to buy a car this week, so it'll be unlikely that I'll find an Elise as it takes a few months to find the right one. Plus, it's probably a waste to get the same car as my boyfriend, it's better to diversify.