I have an oil leak between the engine and transmission of my XC90 V8. I am not sure it is the main seal but maybe. I have a vacuum on the engine. I pulled the dip stick and have suction on the tube. There is a bolt just below the main engine block but high on the cast aluminum oil pan which appears to be weaping oil. This bolt goes through the upper oil pan and into the transmission block. Seems odd it would be leaking as it seems the oil pan gasket just above it is dry.

I posted a picture.

 

Wondering if anyone has any thoughts where the oil is coming from

 

I have the same issue. It may be the main seal. I plan I changing the oil to heavier weight to see if it stops leaking.