color of coolant/oil

What's a dirty coolant look like?
I looked at my coolant reservoir today and there was a crap load of white particles but they weren't floating, so I'm guessing it's not oil. I also saw a lot of black flakes and some metal shavings.

I did an oil change with Mobil1 about 2 1/2 months (1500 miles) ago and it's already turning brown. Do you synthetic guys drive around with brownish oil until 5k+ miles?

I'm also thinking it's the head gaskets, but I was hoping that's not the case..I must have gotten a POS 4.6L, for I only have 7200 miles on it. I lost about 1/2 quart of coolant which I topped off today but it's not burning any oil, yet.