My low coolant light came on 2 days ago and when I checked the level the dipstick was all covered in rust-colored gunk. Do I need to completely flush it? Now I know you can't mix orange/green coolant, so if I top it off what kind of coolant (orange I'm assuming, judging from the gunk) should I get? Sorry about my lack of knowledge on the basics..

 

I would. A friend of mine and myself fixed his 96 3.4 up this past summer and when we pulled the dipstick on his coolant it looked like it was covered with alge. Needless to say we flushed the system (the car hadn't run in a year and a half - the car had moss growing on it!). Two weeks later we drove it down to Myrtle Beach, SC which is a 350 mile drive. Not a single problem until we were about 3/4 of the way back when we lost OD. Had to drive the rest of the way back in 3rd.

 

If your engine uses Dexcool (orange stuff), it should have a sticker near the fill for the coolant. Stick with it, if that is what it has.