When a turbocharger fails it ususally pulls oil into the engine from the compressor side of the turbocharger because of the suction that is created there. This engine oil can leak into the intake, the intercooler and all the hoses on the intake side. You typically will not have to worry about getting it out because the replacement turbo will push that oil out of the engine with pressure. There are cases where a very large amount of oil will be pushed into the intercooler and will not come out. you can remove the intercooler to get it out but in the majority of the cases this will never be an issue.