Mysterious pink fluid in reservoir

[VDCdriver]

This could be evidence of oil contamination of your coolant, and if that is the case, it would likely be the result of a blown head gasket. I would suggest having a competent mechanic (note: Not Jiffy Lube or a chain operation such as Sears or Midas!) check the coolant for the presence of exhaust gases in order to confirm whether your head gasket is leaking. If you ignore it, major engine damage could result in short order.