Intercooler Issue?

I had a similar finding on my 07 CRD.
There was never enough oil residue in my intercooler to warrant a catch can.
I cleaned the intercooler at under 100,000 and again at 150,000 got bugger all crap out of it really.
The intercooler leak looks grotty because the residue attracts dirt and then bakes on there

I used to clean the MAF every 20,000 K's or so but it was never what one would call filthy.

The MAF is upstream of the engine ventilation and can only get oily from turbo surge so maybe the fact that my VNT was wound back a tad reduced the Turbo surge.
It is also turbo surge that puts the oily "ring" on the air filter cartridge

My intercooler looked like that (2010 CRD) and Nissan replaced it under warranty as it was leaking (about 2 months ago). I know they are rubbish but my thinking is that I will save my $$$ now and then buy a new one in 4-5 years when the warranty one craps itself. If yours under warranty, go in and get it replaced.