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Matt, Mechanic
Category: Car
Satisfied Customers: 100
Experience:  10yrs auto, diesel and small engine mechanics training and work. Diploma in engine repair.
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Would like to know the cause of oil in the coolant recovery reservoir

Customer Question

would like to know the cause of oil in the coolant recovery reservoir
Submitted: 8 years ago.
Category: Car
Expert:  Matt replied 8 years ago.
Are you also getting oil residue around the radiator cap area? What you are most likely seeing is sediment build up that happens over time. If you are for sure that it is oil then you may have a head gasket problem. What happens is that oil film will be on the top of your water level and when the radiator cap allows flow to and from the reservoir this film gets pushed into it where it builds up. You should have a pressure test done on your coolant system to check for a possible head gasket leak. Thanks
Customer: replied 8 years ago.
I had an oil change due and the mechanics check all fluids that is when they found this issue I am not having any over heating or missing driving the car. I never would have known there was a problem. I checked the coolant reserve about 3 hours ago and it is just unreal how dark and sure looks like oil all in it. What gets me is that i have my oil changed every 3000 miles and I put alot of miles on this car plus I make sure i take to same people to do oil change could this happen that quick.
Expert:  Matt replied 8 years ago.
If the system was clean at the last oil change, then you may be looking at a serious issue. Oil getting into the coolant that quickly is not good. Did they say if the oil level was low when they serviced it? This would be a sign that oil is getting into the coolant and not the coolant into the oil. You should have the cooling system pressure tested to find out if there is a leak, how major it is and hopefully where.