google it . it is a known fact that synthetic oils do not break down as drastically as conventional oils( breaking down = oil coking) . also watercooled turbos that are properly water cooled run even less chance of failing because of heat .
http://wiki.answers.com/Q/What_is_the_difference_between_synthetic_and_conve ntional
Bailey , the turbo may have failed because of oil starvation , if the oil feed was setup for a BB turbo but it was actually a NON-BB turbo , since BB turbos need alot less oil than NON-BB it could have been the reason for your failure .