Oil draining back to engine from tank

[milfordite]

May not be an issue, but I am curious. On my car, after sitting for a few days or more, there seems to be a fair amount of oil that has gotten back to the engine case. I can see where some would work through the pump, but how much? I was wondering if the filter I have on now, doesn't have a drain back valve to prevent this. When I pulled a lower rocker cover to check the valves, there was quite a bit that came out. Anyone experience something similar?

[Flat6pac]

When the engine shuts down, the oil level will balance between the tank and engine block over a short period of time. If you're removing a bottom valve cover you need to start the engine for a moment to get oil out of the engine case.
Bruce

[Duc Hunter]

I saw someplace that had check valves to prevent this for many 911's. Thought it was a cool idea. Search around....wait...here found it. Rothsport Checkvalves