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Q: Weird green fluid coming out of overflow tank. Right after that, the car almost overheated

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1996 Saturn SL1. Was driving it with no overheating problem, and randomly the temperature gauge started to skyrocket. I parked it overnight. The next day I drove it again, and after about 6 minutes, the temperature gauge started shooting up again. Had to park and let it cool down multiple times while heading back in fear of it blowing up. After I got back to my place, I popped the hood. There was really dirty, dark green milk like fluid oozing out of my overflow tank. Because of the overheating and that, I'm thinking it's the head gasket, but I'm not sure.

My car has 200000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. Unfortunately, it appears as if you may be correct about the head gasket issue - especially when you indicated you noticed that the dark green, "MILKY" fluid. The milky is caused by oil mixed with the coolant; which usually happens when the head gasket lets. The quickest way to narrow out the root source is to check your engine oil. If the oil on the dipstick is also milky, you’ve got a head gasket issue or something that’s causing coolant to enter the oil galley. You might want to contact a local mechanic to inspect it for you to determine exactly what is causing the overheating issue.

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