I ran it for 6 weeks...personally, I think that you get better gains with a 6 week cycle than with four. But, you need to be careful of your liver, and be sure to stay off for awhile after.
I ran 25-30mgs for 8 weeks once, and my liver enzymes were elevated for almost a year afterward. Ever since then, my liver values always go way up whenever I take an oral. (This has happened enough that I've sworn off all dbol and winny for good.) It might just be that my liver has always been very sensitive, but I doubt that since I did cycles before taking dbol and never had problems with my liver. I think that the long dbol cycle may have caused some permanent liver damage