No offense but man you're flushing money down the toilet. The oil will darken quickly but that doesn't mean it is used up. Even the outdated 3000 mile rule is nearly 2x the length you're doing as 3000km is only 1864 miles. How often do you change it, every month? I would be at that rate and I'd be broke.
If you're concerned about the color send it in at 3000km and get it tested. I'd wager they'd be telling you to run it for like 3x that length at the very least
Oh by the way... What air filter do you use again? If you're using K&N, stop. That's probably contributing to the grungy oil look as they do not filter very well and that gunk gets into stuff. Either stock paper or one of those green filters like Hardtrailz uses.