Oil is held on TOP of engine. (L) valve cover stopped up, replaced, but still have same symptoms...boiling smoke on start up and when you check oil, shows very low oil on dipstick because it stays on top of engine.

Engineering flaw with the valve cover, dealer swapped mine out for an updated cover and it solved this problem.

This sounds like a case of clogged oil galleys. These are the passageways that allow the top end of the engine to pass the oil back to the oil pan/crankcase. Though it's an unusual case, this is sometimes caused by excessive engine sludge, gasket media or other foreign deposits lodged in the galleys, etc. If you're able to let the engine sit long enough to try and allow the oil to drain back into the oil pan, remove the valve cover, and look in and around the oil galleys for any deposits or foreign material. They are generally located on the outer skirts of the head. The only time I've ever seen a case like this was from a valve cover gasket that was replaced while leaving the old one inside the rocker panel (head.) Of course, you'll most likely want to replace the valve cover gasket again after this test. Also check to make sure the PCV valve isn't completely clogged either, while you're at it. It's of course a simple, cheap, and much-needed part of a vehicle's maintenance.

Let me know if you need anything else in your diagnosis. I'm here to help! :)