# Oil in coolant reservoir.



## drhaser (Dec 27, 2018)

Hi everyone, 


I have a 2012 Chevy Cruze with a manual transmission (1.8L engine). I recently put my fingers inside the coolant reservoir because it looked really dirty and to my surprise there was a bunch oil in there. The reservoir tank has been looking dirty for a while but I did not make too much of it since I had my water pump replaced at 100k so the coolant was replaced then. The car has 114k on it and I am assuming I have been driving with oil in there for a while. I checked the oil and it looks clean. The car is not overheating and runs really smooth.


After doing some research it seems like its common for the oil cooler seals to fail. Should I replace the whole unit or just the seals? 


Also, I though it would be a good idea to replace the radiator since it's probably contaminated and could fail prematurely. However, to complicate things, I bought the car used and the radiator and AC condenser are bent (due to front end accident). If I were to replace the radiator I probably would have to replace that too? 


Any suggestion/recommendation would be appreciated.


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## snowwy66 (Nov 5, 2017)

I once put trans fluid in the radiator of the semi I drive. It was dark and I had no idea the antifreeze jug was filled with trans and not antifreeze. Drove it for a month before I had to add again and realized what happened. 

Anyways. 

Boss bought some cleaner. 1 gallon. And we flushed out the radiator. 
You drain the antifreeze. Fill with water and run to operating temp. Drain and refill with water and cleaner. Run for 30 minutes with heater on. Drain. Fill with water and run to operating temp. Drain and fill with coolant. 
Worked REALLY good. And the semi holds 14 gallons. The car only holds 6 quarts so you shouldn't need more then a pint of the stuff if it's sold in smaller quantities. 

I don't remember the name of the product now or I'd try to post a google link. It was sold locally though. This was early spring. About 9 months ago.


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## Eddy Cruze (Jan 10, 2014)

snowwy66 said:


> I once put trans fluid in the radiator of the semi I drive. It was dark and I had no idea the antifreeze jug was filled with trans and not antifreeze. Drove it for a month before I had to add again and realized what happened.
> 
> Anyways.


 Have you ever hit anyone in the Semi? I was surprised to read an online application from the company that hit me and the questions were interesting, for example how many accidents have you been involved in, and did any of these incidents lead to death, and what was the total payout involved... Gave me Chills!


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## snowwy66 (Nov 5, 2017)

Eddy Cruze said:


> Have you ever hit anyone in the Semi? I was surprised to read an online application from the company that hit me and the questions were interesting, for example how many accidents have you been involved in, and did any of these incidents lead to death, and what was the total payout involved... Gave me Chills!


Have you ever hit a semi? I watched a dog fly out of a car in my mirrors as the family hit the semi stopped in back of me.

Drive 600 miles a day. I see A LOT of accidents. And some don't end well. 

My semi uses RED antifreeze. And RED trans fluid for the power steering. That we only carry 1 quart. NOT a 1 gallon antifreeze.


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## Robby (Mar 1, 2013)

OP?

You are describing the buildup that occurs on the relatively cool walls of the plastic surge tank. Called 'Phase Separation' it is the visual of the coolant breaking down.
The ideal approach, if you are concerned, is to disconnect the hoses, remove the surge tank, and wash and rinse a few times....I have found Simple Green works ok.....so does a bit of dish detergent.....shaken, not stirred heh heh.

Some coolant will be lost if you take this path.

You have no real problem taking place.....more of a annoyance.

Rob


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## drhaser (Dec 27, 2018)

I guess I will just have to do a thorough cleaning first to see if I get "oil" again. If there was indeed a problem with the oil cooler seal, would a pressure test of the cooling system reveal this?


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## Dieselfever (Feb 23, 2017)

You mentioned that water pump and coolant were replaced 14k ago. Did the one doing the replacement use the correct antifreeze? Mixing non-compatible types of antifreeze can cause sludge in your coolant system. Recommend draining and flushing several times until system is clean. Then refill with 50/50 of the approved coolant for your system.

Yes, a pressure test can and will reveal leaks and problems.


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## ChevyGuy (Dec 13, 2014)

Robby said:


> Called 'Phase Separation' it is the visual of the coolant breaking down.


In that case, I'd think a drain and replace would be a good idea. The 2012 owner's manual says to "Drain, flush, and fill engine cooling system" every 5 years. The 2015 says "Drain and fill engine cooling system", every 5 years. Either way, for a 2012, there's a good chance that it's due.


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## Robby (Mar 1, 2013)

ChevyGuy said:


> In that case, I'd think a drain and replace would be a good idea. The 2012 owner's manual says to "Drain, flush, and fill engine cooling system" every 5 years. The 2015 says "Drain and fill engine cooling system", every 5 years. Either way, for a 2012, there's a good chance that it's due.



Since the OP indicates a water pump replacement has taken place it can be reasonably assumed new coolant was installed in conjunction.
However, even with a chemical flushing process, the coolant in the surge tank gets changed but there is no actual 'flushing' action.

So, back to a formal remove and washout..........BTW....I have to do this to cars that I show about every two years. Surge type or overflow, both designs build this 'mung' on the tank walls.

Rob


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## drhaser (Dec 27, 2018)

I think my post might of have been unclear. I exchanged the coolant the other day and drove it for a couple miles. I did not clean the surge tank yet but I'm pretty convinced now that it is indeed oil in the tank. My question is how do I go about mitigating the damage this will do to the car without spending a fortune? 

Can I replace the radiator without replacing the AC condenser if they are both slightly bent?


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## snowwy66 (Nov 5, 2017)

If the radiator still works and doesn't leak. No need to replace it. 

Just do the degreaser clean as mentioned above. Cleaning out the reservoir tank ONLY or replacing the radiator probably won't do any good as you've probably got that crap inside the entire system. Radator, heater core, water pump, hoses, engine. 

Degreasing will clean out EVERYTHING. And if the problem persists. You've got another problem.

Look for something like this wynn's product. Or maybe something like Prestone. Wynn's products are darn good. Like amsoil products. 
http://www.agmpartscomponents.co.uk...ling-system-degreaser-325ml-bottle-pack-of-6/


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## Robby (Mar 1, 2013)

Oh my! 
That is a lot more evil appearing than I expected.

In general, a failed head gasket near a water passage will show as coolant intermixed with oil....known as a chocolate shake.
Rather rare failure though.....typically four bangers fail the gasket between adjoining cylinders....usually between #'s 2 and three.
It can happen where a high oil pressure passage going through the gasket (think cam bearing feed passage) could fail near a water port but this is highly unlikely. All other oil passage ways are for return and are not under pressure.
So, although not impossible, I'm doubting a head gasket failure.

I have seen coolant intermix with trans fluid in the radiator though and, if you have never changed the trans fluid it becomes rather dark.
This can occur if the trans cooler, built into the side of the radiator, fractures. Because the trans operates at much higher pressure than the cooling system, trans fluid gets forced into the coolant.

With this in mind, DO NOT pressure test the radiator unless the cooler lines are removed from the connections. Otherwise, you will force coolant into the trans.
Under pressure, lines removed, you may find coolant (takes a few minutes) begins to drip from the cooler outlets.

This would require a new radiator (obviously) and a immediate trans flush (since you can be assured a bit of coolant is in there).
The adhesive that is used to hold the friction material to the clutch plates is water soluble and you are hoping the water that may have made it in there has yet to cause damage.

Not intending to freak you out, but the photos indicate the need for immediate attention.

Rob


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