2007 LT with 104000 miles; always has regular service/oil changes/maintenance when needed:
1. PROBLEM: Morning Cold Oil level drops to one line below fill level after sitting overnight /+2 days. If oil is draining back to oil pan, dip stick level is never above full line, always below.
2. To refill to full, takes 2 oz, to stop engine clatter when starting after waiting 20 seconds with key in start position.
3. Dealer says this is normal? but can't explain why or a fix.
4. This problem has just started.
No signs of exhaust smoke, leaks, tailpipe residue, replaced spark plugs 2500 (@103000miles) miles ago, with no oil on old plugs.
Problem goes away for a couple of days, then repeats. I only drive <50 miles local each day.
5. Is PVC system maintenance problem? Other things to check. Will appreciate any technical insight please PM me.
(6. Trade-in /resell value is less than ~$2500.00 so don't want to spend money on a new engine!)

 

Welcome to the site, have a look at the hose that runs from the valve cover to the elbow at the throttle body. It’s been a known place for oil to get sucked out of the engine.

 

Are you usind 5W30 oil? It takes a few minutes for the oil to drain from the top of the engine. The oil cools down and shrinks in volume over night. 2 Oz doesn't make any difference to the engine.

The oil level is acceptable ANYWHERE between the lines of the dip stick (in your Owner Manual).

Engine clatter at cold start is the timing chain.

I guess I just wasted my time typing this, If you don't intend to come back and read it.