If they've never been cleaned and the intercooler never flushed out you may have more than a little too. Every service I have a small amount that's collected.
the intercooler passes charged (pressured) air from the turbo, the turbo runs real hot so they can make them with rubber oil seals in them or they will bake, all turbos will leak a tiny little oil
Please don't send me PM's, i can't access them, when I try I get this:
The intercooler is there to cool down the intake air AFTER it has been through the turbo. The oil is from the turbo, it will let by a little (everyone's does). If you get a lot between services/cleanings (one a year) then it's a tell take sign your turbo is getting a bit tired.
To clean it take the intercooler off the van and flush it out with a can of intake/carb cleaner. Cover one end so it can build up inside and then shake it like a cocktail making sure you get it in all the channels, then let it drain and air out (the carb cleaner will evaporate). Fit it back and job done. The engine might rev by itself slightly or sound a little ropey as it passes and burns off the remaining cleaner.