easy.. For all cars....
Just go to your mechanic... have your radiator removed..There is a general term used by mechanics calledc"chemical wash". Actually what they do is they make a very dilute solution of acid,any readily available,like toilet cleaing solution.
After removing the radiator ...they whah it with that solution and BINGO.
Also condensor needs to be cleaned in the same manner, except that its not removed other wise refrigerent will be lost.
theory is that Radiator fins get clogged with dust and moisture hardens it. hence heat transfer area is reduced. Thus less effective cooling. Simple.
Remember have this done only by and expert..
I,by the way, do it myself.