I really hate to keep this going( so this will be my last comment .. yeah !) the PCV system on the crankcase is only designed to relieve just so much pressure....there is a fixed volume in the crankcase( oil + air = total volume ) adding an excessive ammount of oil will increase the ammount of pressure that the air volume is subjected to and quite possibly overcome the ability of the PCV system to relieve enough pressure......Too much pressure in the engine base will cause leaks at the seals and any compromised gasket surfaces. It is also possible that this level may be reached before there is enough oil to contact the crankshaft lobes. HOW much is TOO much ?? I assume no one here wants to find out. I have been a mechanic for 30 years and wish I had a buck for every time someone has way overfilled with oil and caused themselves problems.

 

The only way and engine will start leaking is from the PCV system becoming clogged. The crankcase builds pressure, and if it can not be relieved (pcv clogged), it will push oil out of the seals.

The PCV commonly carbons up on most engines and causes leaks, not too much oil. My Caddy even had a new intake system because the holes weren't big enough from inception. Later models are fixed.

PS, when you start a post that states the engine gets it's vacuum from the crankcase, no one is going to trust a word you say.

PSS, your cruise control unit has a separate vacuum pump under your air box. It is in no way tied into the engine vaccum...

 

We already established that being 1/8" isn't going to hurt anything.
A LOT of people on here are pretty **** retentive about their stuff, so if you decide to drain some oil out, just take off the oil filter and pour it out and you should be good. May need to do it twice. There really isn't another reasonable way to do it. When I was younger and dumber I tried to take out an extra quart by taking out the drain plug and putting it back in real quickly. Didn't exactly work out if you know what I mean...