My wife's Grand Marquis is the first car I have ever worked on with no radiator cap. The overflow tank is pressurized. Does this mean the coolant level in the tank is the same as in the radiator, or does it blow back and forth with pressure? I am used to just popping the cap and looking at the radiator level.
2009 Mercury Grand Marquis, 8 cyl auto, 80xxx miles, PU
2005 Hyundai Sonata, 4 cyl auto, 93xxx miles, Maxlife
Current oil stash: 516 qts.