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coolant in the oil


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I got my oil analysis back Friday and apparently there may be coolant in my oil, the shop says it is not bad change the oil and drive it for 10,000-20,000 miles, which for me is 3 or 4 years. Should I be concerned? how would coolant be getting in the oil? I assume the head? I am not that concerned but I just thought I would get your thoughts


Here is the text from the oil analysis


All wear levels appear within acceptable limits for first sample. Silicon level (dirt/sealant material) satisfactory. Sodium level (possible coolant chemical) elevated. Water content acceptable. Fuel dilution satisfactory. Please provide missing oilinformation; we need manufacturer, type, and grade to evaluate the oil data. Action: Check for source of possible coolant leak. Advise monitor coolant top-up rate as a precaution. Resample at a reduced service interval to monitor and establish wear trend.

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I've seen this before in my previous truck. You can get a bad sample in a contaminated container pretty easily. If you took it yourself that would not be a factor. Send another sample in after a couple of hundred miles of driving and see what you get. If you did not use Blackstone, send this sample to them. I would not be concerned yet - UNLESS you see coolant levels dropping.

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The text of the oil analysis doesn't seem to indicate that the tech even had his coffee this morning, much less getting excited about the possible coolant contamination.

Jack is right, contamination of the sample is relatively easy. Unless you start seeing obvious water in the oil ( mayonaise like residue on the dip stick) just watch the fluid levels and run it.

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Not sure how you would get actual coolant contamination just taking an oil sample. But, the sample should be taken directly from the drain in a new sample container and not dipped out of the drain pan or put in an old jar.


Oil and coolant do not mix (oil and water). If one drains the engine oil when the engine is cool any coolant should appear from the oil pan drain before oil. You can take a small sample from the first part of an oil drain and put it in a glass jar, let it sit and observe for water in the bottom of the oil.


The only problem with the check above is that oil temperatures can rise above the distillation point of the water/antifreeze mix removing water and leaving behind only the chemical elements of the coolant. Hopefully, your engine oil sump temps won't be reaching the 250F plus point where this begins to occur.


Also, as Jeff noted, oil and coolant agitated in a closed container cohabitate without actually chemically mixing. The result is the mayonayse like tell-tale that can be observed on the dipstick of a cool engine.


Faulty cups and seals in the valve trane can often be the source of fluid intermixing like fuel in oil, fuel in coolant and coolant in oil or fuel. One easy way to check is to put tracer dye in your coolant, run the engine a few hundred miles and then check the other fluids with a UV (black) light source. The UV dye does no harm and can stay in the coolant.

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I had coolant in my oil from tests done at speedco. Nobody could tell me why so I continued to drive 10k miles a month until one morning when I did my pre trip only to see that my coolant was dark with oil. Prior to this there had never been an indication of oil in the coolant, only coolant in the oil. I have a Cummins 530. Both of my oil coolers had failed. Once they were replaced it was a ok.

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Worst case would be if you were running Prestone regular type antifreeze, and not staying up with the

Nitrites which would send the "PH" readings dangerously out of balance. This condition can eat right

through the steel block. This condition isn't that prevalent these days but nothing says it isn't still a possibility, Just a thought.




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