Milky oil, yet full coolant reservoir.

[Valkyria90]

Removed the oil cap on my 2017 Civic 1.5T Sedan today and got very worried when I saw a milky substance on my (aftermarket) oil cap. I had an oil change back in january, and this is the first time inspecting the oil cap since then.

My immediate fear was a broken headgasket since a milky oil cap is a textbook symptom of that, however my coolant resevoir is still on the "max" level. I borrowed a tester kit for broken head gaskets from a buddy of mine (the one with blu dye that will turn yellow if there is a leak detected) and even with the car running at operating temperature for 20+ minutes there was still no change to the dye.

So the obvious question is why is there water in my oil coming from if not the coolant? Could the oil they used when they changed it be compromised or something? For all intents and purposes I have not felt any stutters, hard starts, lack of power etc. I just discovered this randomly when removing my oil cap.

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[BoxsterSteve]

Check the oil on the dipstick too.
If the oil in the crankcase checks out clean and there’s no milkshake in the cooling system, it’s just a cold weather/short trip thing.
Its what ICE vehicles can do in the winter if they are short tripped and not allowed to warm up fully to burn off built up condensation.
A typical gasoline engine produces about a gallon of condensation for every gallon of fuel burned.
Seeing you’re from Norway in the wintertime, that would be my best bet.

 

[Valkyria90]

Good to know it's a relative benign problem. I know the 1.5 is very slow to warm up. My daily commute is about 20 minutes so I guess it's too short of a ride to fully burn off the condensation and vapours. I will probably do another oil change myself come spring so at least the problem will be mitigated as much as possible

 

[Gruber]

Good to know it's a relative benign problem. I know the 1.5 is very slow to warm up. My daily commute is about 20 minutes so I guess it's too short of a ride to fully burn off the condensation and vapours. I will probably do another oil change myself come spring so at least the problem will be mitigated as much as possible

That's one of the reasons why all ICE engines don't like short trips, not only GDI. And the main reason why oil needs to be changed even if the car is driven very little. Water does create acidic conditions and may decompose (hydrolyze) some additives over time. I would also make sure that your aftermarket aluminum cap seals tightly. These range in price between $10 and $80+.....



https://www.carbibles.com/milky-oil-cap/

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