a few months back i had the same...some crud floating on the top of otherwise fine looking coolant,coolant tank cap was a little milky.I topped the coolant right up and the crud overflowed out,took a little coolant out,fine since.However I am back to my longer commute too,40 kilometres or so each way,car is well warmed up each day.I had been doing a much shorter trip,only about 15 kilometres,car hardly warmed up...