So any of you in eastern (well, GTA and eastwards) Canada will have just dealt with our first big snow storm. Unfortunately I was caught in the thick of it (can you believe 2 hours from Mississauga to Hamilton??), and the snow was so bad on the driveway, I just didn't move my car for 2 days when I got home.
So I moved it yesterday, and noticed a bright yellow, maybe you could call it greenish, dripping in the fresh white snow. It ran along the centre of the car, and there was a little bit heading towards the rear left wheel, but not so close to be a caliper. I'm 99% sure it's not brake fluid, since I checked the colour of some DOT4 I had on hand, and it didn't seem so bright, though I didn't put any in the snow. And of course, it's not coolant, since we all know G12 is pink.
After some googling, I came up with the possibility of the snow reacting with rusty heat shields, although I'm still not sure on the colour issue (Some RAV4 forums came up with this).
I've had my car rustproofed this year, about a month and a half to 2 months ago, so that's one possibility. I have no idea what colour the Krown stuff is...I just take it in and let them work their magic. No issues on the hour to my dad's, nor the hour back, nor the numerous errands in between.
Maybe; take some out and throw it on the snow for comparison. BUT, the OP called it a "bright yellow/green". The VW PS fluid is a dark green in the bottle, and pretty much black in most peoples reservoirs. Nothing "bright" about it, and yellow isn't the first thing that would come into my mind.