seems my 04 has an oil leak, looks like it is coming from behind where the oil filter is. Is there a seal behind where the oil filter unit is and the motor? I dont know what it is call, the filter screws into this unit, it has 2 lines going through it for coolant. My oil leak is coming from behind that. How dop you get it off and is there a o-ring/gasket back behind that may have gone bad?

 

The unit you're referring to is called the oil cooler, behind the oil cooler is an O-ring which you stated earlier in your post. Pictures are worth a thousand words, see attached link for write up.

http://my6thgen.org/f107/oil-cooler-ring-swap-16041/

Once you have completed the install, make sure you burp the system while installing coolant in your system or the heat might not work properly in your car.