Milky Oil Cap but Not Dipstick – What Does It Mean? (Explained)

Have you ever noticed that your engine oil cap has a milky residue but not on your dipstick? Many people have been asking about this when they checked their engine oil cap, and it has milky oil. But when they tucked the dipstick in, the oil was clean and good.

So what does it mean if your engine oil cap has milky oil but not in the dipstick? If this happens, it means there is condensation. This can be caused by a car that is not driven frequently or a change in weather conditions.

If you have milky oil only in the engine oil cap, there is strong evidence that there is just condensation. You will not have to worry about your head gasket leaking or having engine damage. This is a good sign. 

So let us learn more about this milky oil cap.

Milky Oil Cap but Not Dipstick

What Does Milky Residue on Oil Cap Mean?

If your oil cap has a milky residue in it, that is called milky oil. If your engine gets mixed up with water, then you will have milky oil. You will have a milky residue on your engine oil cap if there is condensation. 

This condensation happens a lot for cars that are not driven frequently. If you have short trips or drives, the engine will not be given enough time to burn off the engine’s water vapors. In return, this water vapor will build up and accumulate. 

This will then become a milky foam in the engine oil cap. Another possible reason also is if there are sudden changes in the weather. If there are changes in the weather and the car is just idling at home, this milky oil will become more frequent. 

If moisture or water is mixed up with the motor oil in your engine, this will create a milky foam in your engine oil cap. This can be caused by condensation, as mentioned earlier, or you leak your head gasket. 

If there is a leak in your head gasket, the coolant will get mixed up with the engine oil. This is a more severe problem. It would be best if you fixed this right away. 

This happens because of the coolant getting mixed up on your engine oil. This can be caused by a leak in the head gasket, which can be caused by damage to the engine. With both, it is dangerous and requires immediate attention and immediate fixing.

Should You Be Worried About Milky Residue on Oil Cap?

Of course! As a driver, you need to know that motor oil is considered the blood of a vehicle. The motor oil keeps the car in a good performance. When your car is running, the engine will also have its moving parts. 

These moving parts will then create heat from the friction. The job now of the motor oil is to keep these moving parts well lubricated. In return, this will avoid any tear or break in your car’s engine. 

So the motor oil must remain clean and free of any contamination at all times if you have a milky residue in your oil cap, which could mean that your engine oil is dirty or contaminated. Milky oil is caused by contamination of water or can be any foreign substance. 

If your motor oil is contaminated with water, it will lose its thickness, and it will not be able to do its job of lubricating your car’s engine. So if you will see a milky residue in your oil cap, you must not take this for granted. 

You need to flush this milky residue and keep your oil clean and new at all times. Having a milky residue in your oil cap might mean that the engine’s oil is also dirty. If that is the case, your engine will not be fully and adequately lubricated. 

So once you see a milky residue on your oil cap, clean the residue and check your engine oil. Replace the oil if necessary and consult a service center if necessary.

clean dipstick

What Should You Do When You Have Milky Residue on Oil Cap?

Before fixing the milky residue on the oil cap, make sure that you already know its cause. There will be no point in removing the milky residue in your oil cap and not fixing the issue. The issue will persist all the time. 

So you can get rid of this milky oil by flushing the engine with flushing oil. By flushing your engine with flushing oil, you will remove the white foam in your engine oil cap. When doing this, you have to make sure that your breathers are clean. 

You also have to use a new oil. Refill and use new oil to eliminate your chosen oil as a cause of the problem. There is oil that is not high quality that can also cause this problem. To avoid that, change your chosen oil brand. 

Having a condensation like this in your motor oil is not good. You need to immediately find the problem and the cause of this milky oil. After finding the problem, fix it immediately so that your oil will remain free of any water or decontamination.


In summary, you might have milky oil in your engine oil cap but not in the dipstick when you check your oil. This is a good sign. This is mainly because of condensation. 

This happens when a car is stationary or there is a change in weather conditions. Have it fix right away so that you can avoid any problems in the future.



Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more