I must start by apologizing for the errors in the explanation for how the Egr tube started it all. This was originally spread out on 5 pieces of Post it notes and after many interuptions, it still took me half an afternoon to finish the post. I called Keith for a clarification.
Once a small amount of carbon starts building on the inside of this tube, the computer reads it's effect on flow and riches up the fuel. This washes out the rings and small amounts of raw gas begin to contaminate your oil, bearings don't like this. After a short while, combustion gases start getting past the rings placing more crankcase pressure on the pcv system, sucking gas diluted oil up into the intake to further add to the carbon buildup in the tube and confuse the computer. ( ever have an intermittant CEL that kept insisting the upstream oxy's were a problem?) It was not the egr tube that would be plugged on blown motors, it was the pcv valve and lines. The fuel contaminated/low oil conditions damaged the rings. Mine is scheduled for this service and I will share my results.