93,000 miles, 4000 miles after my last oil change, the dipstick came out bone dry. It didn't lose any oil between the last two changes, but all of a sudden, it took 2 quarts to top off. B230F turbo engine, the filler cap danced around in the rattle test and there seemed to be zero or positive pressure in the crank case (put my hand over it), so I removed the oil separator and hoses, and sort of cleaned the separator box, flushed it with water, Simple Green, and Greased Lightning. A lot of gunk came out at least. Also cleaned out the small plastic nipple on the Y-joint above the box (almost completely plugged). The hoses seemed ok. Put it back together, and now there seems to be a little vacuum in the crank case, the cap still dances around, but it's the plastic one, if I lift and lower the cap I can feel it get sucked down a little. Then I got a paper towel and held it over the filler hole, instead of getting sucked down as I expected, it vibrates up and down, going from concave to convex, at the frequency of the engine I think. Sorry about all the rambling, but should it do that or get sucked down? How much negative pressure should there be?

Thanks,
Richard
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'90 744 tic