Rear main seal question. How oil-tight?

So I ran the 5.3 Vortec on the stand for a good half hour or so. The goal was to make sure that the rear main did not leak oil. Not a drop detected, so I pulled it off the run stand and put it on an engine stand.

The engine stand is one that holds the engine tilted back at an angle.

The engine has a shallow oil pan ( Holley 302-2 ) 

Because of the shallow pan and the angle of the engine, I am pretty sure that the inside of the rear main is flooded with oil. Said oil found on the floor the next day.

Question now is do I have a rear main seal issue or is the seal not designed to hold back a pool of oil on the inside?

So new rear main correct? Just the rear main or the whole cover and gasket too? Did you use an installer tool? Did the seal fit tight on the crank?

Might be the spring itself is a bit long and not holding enough pressure against the crank resulting in the stationary oil leak.

You may have dislodged the garter spring when you drove the seal in.

I always pack the back side of the seal with grease to help stop this from happening. 

This is the second seal I installed. The first  poured oil out after a short run.  This one was bone dry while running on the test stand.

This was as dry as long as the engine is not tipped back to where the oil comes over the pan and floods against the seal.

New seal used the aluminum block  install ring gizmo to center the cover. Not a new rear cover.

Sounds like the answer is that this seal should  be able to hold back an oil level that is above the seal indefinitely if it is work ing properly.  

I actually built the run stand to test for leaking rear seal since they seem to be common problems with the LS installs. I would rather trouble-shoot this on the stand rather than under the car. Now I know that just tipping the engine forward or rearward to flood the seal will tell me if they are good to go.

Do the flywheel bolt holes go through to oil, and if so did you put sealant or Loctite on the bolts?

In reply to Pete. (l33t FS) :

yep, remembered that one. 

In reply to Pete. (l33t FS) :

yep, remembered that one. 

This is not my area of expertise, but I would think if that slight angle is to blame for the oil weeping, mild (or greater) acceleration would likely have the same effect.

Well, the problem is solved. Big DUH moment and circumstances of how I stored the engine.

The problem was this little doinkus that bolts on over the oil filter. I had one that I made for the test stand so that I could read the oil pressure with a mechanical gauge. Well, that came off and stayed with the test stand since we were testing other engines.

When I stored the L33 on the engine stand, I bagged it up in a big plastic  construction garbage bag. So I could not see the filter area. Oil leaking out due to the tilt migrated to the middle of the bag  that just happened to coincide with the area right under the rear main and dribbled out. 

Was so very happy as I smacked myself on the forehead.