As time goes on you will definitely have some oil build up in your Intercooler. This can effect the efficiency of it. It is very easy to clean out and might take 10 mins. First thing to do is get the IC off. You have to remove the four 12mm bolts holding it on (red). Take off the two connecting hoses (yellow). and loosen the two 10mm intake pipe hose clamps (blue). Now from the driver's side (right hand drive...) lift up on the IC to get it off the intake pipe. After it's up pull it towards you to get the other pipe off.
Now the easiest and cheaper way to clean it is too run gas through it, but I didn't have any on me and I had an almost full can of intake cleaner left from cleaning the BAC valve. Just keep running stuff through it till it comes out clean. When I was finished I ran a hose through it too; but if you do you have to let it sit for a while as it dries. Install in the reverse order. Make sure all the clamps are back on and also the coolant line bracket held by one of the bolts on the pass. side.