I follow the manufacturers schedule for changing oil. On the average, no more or less than 5000 miles between changes. The SLKs mileage is still too low to change until the manufacturers scheduled oil change. I like the synthetic oils available and I'm willing to pay extra for that quality oil. I'm not partial to any particular brand, but I wouldn't use the cheap off brands. I've never had a vehicle in my lifetime with ANY engine problems. Changing oil with less mileage than what's recommended is a waste of money in my opinion. I also prefer to do my own oil changes. The MB will be the exception while it's under warranty. I normally don't return to the dealer for scheduled maintenance on my other vehicles.