NZ Benz

Hi there, Im new here and looking to getting a merc and had a few questions reguarding the W126 S-class as over the Summer during New Years week ( in nz its summer over new years) and was given a '86 420se to use at my disposil for that week which was awsome, and i fell in love with it and now im considering gettng one.. the only thing that im concerned about is the matinence on one should i buy one. i know i should have done a search ( which i will do) but i was wondering if someone can note down a few common problems the w126 s-classes have
thanks in advance