I just finished replacing the turbo and would first like to thank John for his help. The replacement took barely three hours. Would have tackled it sooner if I knew the Mitsubishi's were so easy.
When I removed the old 13c there was oil caked throughout the turbo. Even the BOV diaphagm was plastered with it. There was also a heavy brownish white carbon deposit coating the exhaust turbine blades, I didn't notice any excessive bearing play in the turbo shaft though.
Could this just be an issue with the old turbo, or perhaps a plugged EGR system.
The car has only 125,000 miles and doesn't use any oil, so I doubt that the rings are are the issue.