I second that notion. The PCV valve (Positive Crankcase Ventilation) allows blow-by gasses that enter the crankcase to vent out, while sealing the crankcase when it holds a vacuum. A vacuum is normal and desired - that's what drives all of the vacuum-bases systems on the vehicle. If your PCV valve is plugged, pressure will build and will blow oil out of any feasible point and may blow seals and/or gaskets. A bad PCV valve may be the problem. Or it could exacerbate another problem, such as worn rings. The valve is only a few bucks to replace and it's easy to do. Blown seals, like your rear main, can be a real pain in the <img src="/forums/images/graemlins/butwiggle.gif" alt="" />, as you well-know. Check your PCV valve. If it doesn't rattle, get a new one.

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