HELP! Coolant is rusty brown only 30K!

[TheSilkySmooth]

My Coolant reservoir is low about and inch so I did a cold check on the level under the rad cap and noticed the coolant color is like a tan muddy or rusty brown. The Coolant in the resev is a red color. The car is a 2008 with 30K miles and I JUST had a 30K checkup. Is this color on aged coolant NORMAL or do I have a problem? The car had been acting odd the past couple days with unstable idle and rough running. I have noticed no steam out the tail pipe - but I wasnt looking for it either. I Also notice no oil in the coolant, but it was low just a couple OZ so I filled to top of rad cap with distilled H2O and closed it up. Does the 2008 use the red or the oink stuff - or are they interchange-able?