Apparently even GM knows most people change their oil too frequently...
They're not the only ones:
That's not an indicator of how dirty the oil is.
Different oils break down at different rates, and even the same oil can break down at different rates depending upon riding habits. Why, again, does Honda call for an oil change at 1000 miles on the XR600, and 2000 miles on the XR650L? I'll guarantee it's because the XR600 is designed to be used in severe service conditions, exactly how I'm using my L. 1000 miles it is, for me.