Coolant reservoir smells and looks like oil inside, but the oil looks clean. Car has yet to overheat and no visible leaks on the ground. Only place coolant has leaked is through the cap which I replaced but still at some points still leaks through there. Any ideas what the problem could be?
My car has 100000 miles.
My car has an automatic transmission.
One of the common problems with other vehicles like you’re 95 Cougar is that the overflow coolant reservoir can collect mold and fungus over time; especially if water has been used in the past instead of straight or pre-blended coolant. This is most likely what is the clear oily looking substance. The only solution here is to replace the coolant overflow reservoir as well as the coolant lines leading from the unit (as they also might have mold inside them).
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