cleaning oil out of cooling system

Status
Not open for further replies.
Joined
Aug 14, 2010
Messages
12,968
Location
Northern Kentucky
I have some leftover oil in my cooling system from bad gaskets. 2002 buick century. They did a flush when they put the new engine in but didn't get it all out. They refilled it with the green anti-freeze.

What should i use to get the oil out of the system and should i re-fill it with dexcool?
 
We use simple green. Drain a couple of qts out and put the simple green in. Run the engine an hr or so then flush with water. May take a few times to get all the simple green out. If the car has a cap on The radiator I don't recommend dexcool. If it has a pressurized bottle with a cap dex is ok.
 
The car does have a cap on the rad and then the overflow tank is where i spotted the oil.

How is the cap relevant to using dex cool or not?
 
It may not really be oil but corrosion floating out the top. I've seen it look and feel just like oil but it was just corrosion. But make sure you're not losing transmission fluid into the coolant.

The reasoning for not using Dexcool with the cap on the radiator is those system don't always do a good job of keeping the cooling system completely full which is need with Dexcool. It can be done though if the system doesn't have leaks with measures like a Stant 10230 radiator cap, Havoline Dexcool and keeping the radiator full and filling the overflow above the hot line.

Here's an old service bulletin:

Subject: Brown Colored Gel-Like Substance on Radiator Cap and Upper Filler Neck (Replace Radiator Cap and Clean Radiator Upper Filler Neck)


Models: 1997-2000 Buick Century
1996 Chevrolet Lumina APV
1996-2000 Chevrolet Lumina, Monte Carlo
1997-2000 Chevrolet Venture
2000 Chevrolet Impala
1996-97 Oldsmobile Cutlass Supreme
1996-2000 Oldsmobile Silhouette
1996-97 Pontiac Trans Sport
1996-2000 Pontiac Grand Prix
1998-2000 Pontiac Montana
with 3.1L or 3.4L Engine (VINs J, M, E, X -- RPOs LG8, L82, LA1, LQ1)


Condition:
Some customers may comment about a brown colored gel-like substance on the radiator cap and upper filler neck.


Correction:
Important
This condition is unique to the 3.1L and 3.4L engines and should not be confused with the condition described in Corporate Bulletin Number 99-06-02-012B -- Rust in Coolant System.
This condition is almost always confined to the radiator cap and upper filler neck, so it is not necessary to change the coolant. Keeping the cooling system full at all times should eliminate future recurrence. Replace the radiator cap and clean the radiator upper filler neck using the procedure and part numbers listed below.
Remove the radiator cap when the engine is cool.
Slowly rotate the cap counterclockwise to detent. Do not press down while rotating the pressure cap.
Wait until any residual pressure (indicated by a hissing sound) is relieved.
After all hissing stops, continue to rotate counterclockwise until the cap is removed.
Using a shop rag, clean the upper radiator filler neck of any residue.
Remove the coolant recovery reservoir if visually contaminated. Refer to the Coolant Recovery Reservoir Replacement procedure in the Engine Cooling sub-section of the appropriate Service Manual.
If necessary, clean the coolant recovery reservoir and all holes attached to it with soap and water. Rinse the reservoir and hoses with clean water and drain. Verify that the coolant can flow freely through the hoses.
Install the coolant recovery reservoir. Refer to the Coolant Recovery Reservoir Replacement procedure in the Engine Cooling sub-section of the appropriate Service Manual.
Refill the coolant recovery reservoir with a 50/50 mixture of DEX-COOL® and clean drinkable or distilled water to the HOT mark. Fill to the HOT mark to compensate for any air that may be in the cooling system.
Fill the radiator to the top of the filler neck.
Install the new radiator cap, P/N 10409635, making certain the arrows line up with the overflow tube.
Instruct the customer of the importance of maintaining the proper coolant level in the radiator and coolant recovery reservoir.


Parts Information:
Part Number Description

10409635 Cap, Radiator Filler


Parts are currently available from GMSPO


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
 
Last edited:
It's hard to tell, but motor oil getting into the coolant is pretty rare. You're left with indirectly looking for motor oil loss, coolant loss (or gain), and ATF loss that's not leaking externally. If the fluid levels are steady then the coolant is most likely just corroded.
 
Do people send this stuff in for a uoa?

I'll probably just flush the system with some over the counter radiator flush like the prestone super radiator flush and replace or clean the overflow tank. It bothers me how discolored the tanks get and you can't tell how low the coolant is because it's not see through anymore.

If they are expensive though I'll probably just clean it.
 
There is coolant analysis, but it's not talked about much even on here. I don't know if it would be able to analyze the coolant for oil or not. They would tell you the coolant is dark (duh) and give values for the pH,inhibitor levels, corrosion metals levels etc. But I'm not sure if the analysis would tell you if you have motor oil or ATF in it.
 
Originally Posted By: mechanicx
But I'm not sure if the analysis would tell you if you have motor oil or ATF in it.


I just looked at an old one from Oil Analyzers here. It looks like they have categories for magnesium and calcium as contaminants. I'm assuming those would be expected to come from motor oil if they appeared in a coolant analysis.
 
The problem is that some DexVI fluids seem to use Ca as an additive at low levels, and many motor oils don't use Mg at all.
 
Well, I made a shot.
wink.gif
And low level Ca additives could mask low level oil intrusion, much the same as Na in oils with sodium additive packs. Serious oil contamination would be pretty obvious, one would think. Nonetheless, I haven't looked at other coolant analysis sheets other than the Oil Analyzers ones. Maybe I'll have to read some of the posts.
 
I'm thinking they switched from dex cool to the green stuff that's in there now and didn't get all the dex out.


I'll probably flush it and re fill with something green.
 
That's a very good possibility, mixing and diluted partial amount of two types and different dye colors can lead to a brown color and even corrosion. It's not necessarily the fault of the Dexcool or the other coolant but the mixing of both.
 
There's original green formula that Peak and Zerex carries. Zerex, Ford or Chrysler G-05 is another option that is prety similar to orginal green. Peak Global is an option but I'm not a fan and don't see it as being better than or really as good as Dexcool.

The main thing is to get 1/2 system capacity of concentrate regardless of which formula you choose. I would use either original green formula, Havoline or Zerex Dexcool or maybe G05.
 
Since it's already full of mostly green stuff I'll probably stick with it. Is the prestone green stuff in the yellow bottle as good as peak or havoline?
 
I think I'm going to try the peak PKA0G3/12016 which seems to be the correct peak product.

Which havoline or zerex product is the compatible EG Product? There's lots of different jugs and i might buy online.
 
Yeah I think that is Peak's original green formula. I don't have the product code numbers but Zerex also labels their version as "original green formula" and Havoline calls its original green formula "conventional".

NAPA would be a local source for Zerex original formula and also for Havoline Dexcool but it sounds like you are going go with convential green.
 
Status
Not open for further replies.
Back
Top