Oil Leak in TR182

I have an ongoing, frustrating oil leak that four mechanics have looked at,
"fixed", charged me over $1,000, and have not made a dent in stopping.

So here are the clues I can offer. Any help is GREATLY appreciated!

1) I am going through a quart every 2-3 hours

2) The oil is getting down into the belly. When I lower my gear after a 2-4
hour flight the left gear is streaked with oil. Oil also drips from the
belly.

3) So far I have removed and checked the lines from the M20 oil-air
separater, checked all the lines to and from the breather.

4) Like all '79 TR182s, the oil runs hot, especially on climb out. I have
replaced the valve that opens the flow through the oil cooler (can't
remember what it is called - a "verner valve ?") and that helped
significantly.

5) Compression is good on 5 cylinders, marginal on one.

6) I keep the oil at about 6 quarts. If I fill it to 8 I just blow out the
top two qts.

7) The engine has about 900 hours.

8) There is no leaking visible or residue anywhere around the top of the
engine, filler, the dipstick, or the pan.

Thanks in advance for any ideas. Not even sure where to start trouble
shooting next.

Michael