The Mercury white you are seeking has been described here by automotive paint specialists here as PPG or Sikkens light cream white. Only under neon test lighting can you even begin to tell the test chips apart so that is what people are doing around here is using either. I hope that helps.

I sorted the paint for my white 200 Merc by taking a piece of it (the corect colour) to the local car paint factors, they colur matched and tinted some paint specially, they like to do 1 litre or more...they can even put your paint in a spray can if you want...you should have a auto paint factors around you somewhere...hope it helps. They will match faded/creamed white so make sure the bit you supply as a pattern is the final colour you want.