I'm asking only because after only 3 or 4 months since I replaced my radiator, I have what looks like a mad amount of brown rust in my coolant. It initially looked orange, like the shop put dexcool in the system. Doesn't that stuff rust out the cooling systems on cars? I thought it was oil in the coolant at first, but I haven't lost any coolant in 2500 miles and it's clean.