If you're saying you've got milkiness, chunks or signs of other issues, then that's something completely different and we need to figure out why you're having this problem, because a flush won't help.
8k intervals isn't anything special, so long as you maintained the oil level on the dipstick. Did you maintain the oil level or has it ever gone low or do you simply change it every 8k and never check between changes? What's your oil consumption.
Finally, what do you mean by disgusting? If you're saying that your oil is coming out dark, then just keep doing what you're doing - no more answers needed, nothing's wrong, and what you've been doing will work well from now until the car falls apart. End of thread.