[NikiterZTS]

I'm gonna chime in here. Whenever I do my oil changes I do it with Motul 5W30 (pretty expensive stuff, $65 for 5L jug). For some reason I started noticing that my oil would get dark by like 2000km (don't matter if I tracked my car or not that month). So to be on the sure side contacted BlackStone labs and they sent me out their test container for my spent oil. So oil change time came around at 5000km (at 1000km mark I went winter lapping, car saw a lot of high RMPs:-)). Sent it out to them and got my report over email probably a week if not less later.
Now I can't find this damn report cause I probably accidently deleted it but they stated that my Subi engine is in top shape and that I can no problem go to up to 6000km mark.

Now all I'm saying if you're gonna run synthetic oil and most likely you don't track you beast then you can go up to 6000km no problem.

Link for testing facility:
http://www.blackstone-labs.com/free-test-kits.php