Main steps of the Oil Filter Adapter/Housing and/or gasket replacement on Cadillac CTS 3.6L 2008 - 2013
1) Remove the intake manifold cover, disconnect the battery (in the trunk), remove oil filter from the housing. Drain the oil. Remove the Air Filter Housing. Remove the tank/reservoir for power steering fluid (2 bolts: 10mm and 18mm, don't disconnect the lines)
2) Take off the serpentine (drive) belt
3) Remove Power Steering Pump (don't disconnect the lines). This works includes removing the pressed pulley
4) Reposition the AC Compressor (don't disconnect the lines) - 4 bolts
5) Remove the Oil Filter Adapter (5 bolts)
This is really difficult work, could take several hours and cost about 500 - 700 USD. There are no video on youtube dedicated to this work.