Offshoreonly.com - Some more 525 questions

Ok, this one has to do with the cooling system. In my resivoir tank, I see the pink stuff, but I also see a black layer on top of it. It's been there since before I bought the boat (have dealer pics), but I really didn't notice the difference until I saw a new 525's coolant tank and how pink it looked from a distance. I thought it was just bad light in my photo, but I got down there and looked yesterday and could see the stuff on the side and since the boat was sitting butt low on the trailer, it was pretty thick at the back of the tank. I hope it's not the 'O' word in my tank. :eek: The engine runs fine, my oil temp is never over 200 and my water temp is a little above 150. I have put about 30 hrs on it since purchase and it will get an oil change before its next outing. I did check the oil and it was down to the add line. My 350 mag burned oil off too, but is it normal for the 525? Can oil get into the cooling system? This stuff is floating on top of the pink stuff but I can't see it too well with the cap off. Right now the plan is to drain that coolant tank and refill with Dexcool. Any thoughts on this matter are appreciated, I hope it's nothing serious, like I said before engine runs great.