Looking under my hood today I noticed the reservoir looked kinda dark. I decided to dump it into a separate clear container to inspect it a little further. So it still has a green tint, but just looks dirty. I did notice that the very top is still bright green, so I'm hoping to put my fear of oil to bed. Radiator is fairly new, put on in the last 2 years, tops. Car hasn't been driven for about 2 months. My guess is that it's rust from the system. I just wanted a little confirmation before I flush the system and start driving it regularly again.