In my opinion, the mileage between oil changes should vary somewhat depending on the crankcase capacity (oil volume). The more oil, the more crud it can suspend, just stands to reason.
For most people, assuming combined city and highway driving, I recommend 1000 miles per every quart of capacity. So most domestics, holding 4 or 5 quarts, means 4000 to 5000 miles. On MB's, most hold more than that. Most V8's hold 8.5 quarts roughly, so 8000 miles or thereabouts doesn't seem unreasonable.

Gilly