Auto Parts and Repairs
Oil and Oil Filters
Antifreeze and Engine Coolant

What would cause oil to leak into the antifreeze reservoir?

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2011-09-13 17:54:42
2011-09-13 17:54:42

Consider if it is engine oil or transmission oil or power steering oil. Transmission oil or power steering oil would indicate a bad radiator. Engine oil could be a bad radiator also if the radiator includes an engine oil cooler ("extra cooling") but usually indicates an intake or head gasket leaking.


Your symptoms are indicating a possible head gasket problem. If you have oil in the water, you may have water in the oil. Pull out the dipstick or take off the oil fill cap and look for the unusual condition of FOAMY oil. You may also have exhaust gas in the water which can also be checked by a mechanic. Be prepared for the expense of a head gasket or possible engine replacement.


if you have oil in coolant, you have a cracked head or a cracked block your mechanic will do a compression test to determine what it is either way it is not cheap fix unless you can do it yourself


you may have a blown head gasket, or cracked head , or cracked block


It could be a number of things listed above. However I had this issue with my 3.1 V6 GM engine. I had oil in the coolant, and it turned out to be a failed Intake Manifold Gasket. It is best to take it to a repair shop and let a professional handle it unless you are mechanically inclined. If it is an Intake Manifold Gasket your looking at a ball park figure between 400 to 900 dollars. Think of it this way, would it be more beneficial to fix your current car? Or to go and put a down payment on a new one and get stuck with payments for the next 5 years?


It seems everyone assumes that you are talking about a gasoline engine which for the most part they would be right: radiator oil/trans-fluid internal cooler, intake leak or head gasket. If you are talking about a diesel engine, could also be oil cooler o-rings, cylinder liner o-rings, failed e.g.r. cooler, etc.

i think its funny that i have that same problem with my 3.1 v6 gm motor and my friends grandmom had the same problem lol and there is oil in my reservoir alott and if u want to know if u bad head gaskets u wont be able to see people behind u because ull be pouring white smoke out of ur exhaust, and whoever said water is heavier then oil is retarted its less dense then water yes but not heavier its hard to tell what the exact problem is so first things first id do the intake manifold gasket one because the part is cheap and to its not exactly ripping ur motor apart

yes lets tell this person to fix there exhaust manifold because that takes care of his oil & water problem. the person that feels not pulling an engine apart, how do u fix a a hungry stomach. now this person has oil in the water not an exhaut minifold problem geeezzzz some people.....

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If it is motor oil in the anti freeze, then it is either a cracked head, cracked engine block, or a head gasket blown. If it is transmission fluid in your antifreeze, then the radiator is leaking from the transmission cooler ----- although usually that would cause antifreeze to be in your transmission fluid.

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1996 and up Taurus cars have a problem with cracking on the bottom of the reservoir. I have replaced the tank on all three of my familys Tauruses because two had hairline cracks that would leave antifreeze on the ground near the reservoir.

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