Jimm 8/25/2012Engine oil getting into the cooling system is an indication of; faulty head gasket or faulty cylinder head seal. If the oil is transmission fluid, then this would be related to a faulty radiator transmission cooling tank (leak internal to the radiator).
Jimm 8/26/2012An oil filter with a water jacket? The oil filter design for your vehicle is a spin-on, full-flow canister type - with these dimensions; O.D. 2.99"; Inside Diam/Thread 3/4"-16; Height 4.84" (112.8 mm). There is no water jacket for the engine oil filter on the 2.0L engine.
There aren't too many routes for engine oil to get mixed into the coolant - except via a leaking gasket or seal inside the engine. It could be that you are experiencing the oil / coolant leak at it's early stage - before it can affect the engine performance.
Have an inexpensive cylinder compression test performed - both wet and dry, or borrow the compression tester from any local auto parts store, such as; Advance Auto, Auto Zone, NAPA.
monteur 8/26/2012Replace the engine oil cooler which is located above the oil filter.