Pull the cooler off and check for oil in it. If it has a film of oil it neads rebuilding. The stock IHI turbo is maxed out at 18 lbs. If you waht to run higher boost you will a T3 T4 hybrid The stock ihi is a very reliable turbo. But the seals can go. Check the backlash on the turbine. If there is any play its turbo time.

Never run a heavy oil in a turbo 2.3 NEVER NEVER EVER. :nono:

The bottom end of the 2.3 is very strong. And the valve seals are neoprine and also very strong. But the turbo is not so strong (seal wise). The fact that you are seeing oil after a warm up makes me tend to believe its the turbo seals. It could very well be a combination of all three but i dought it. I run the new honda light oil in my TC engine. And never use an oil heavier than 5W30. Unless its always hot in your state like FLORIDA.:bigthumbsup:gringreen