I'm using a synthetic blend (Castrol) and Mann filters. The oil and filter are changed every 6-8 weeks; this car covers an average of 1,000 miles a week, sometimes more, never less. I figure that since I'm covering 6-8K miles in several weeks vs. several months, it's not that big of a deal. The car doesn't appear to burn any oil and it still looks relatively clean when changed. Could I extend the interval even longer, or am I asking for engine problems down the road?

The owner's manual recommends an oil change interval of 7,500 miles. I wonder how many 240s that had oil changed @ 7500 mi. intervals made it past 100K without major engine probs.