The engine may experience serious issues as a result of oil foaming. Small air bubbles that gradually build up in the oil cause foam. Overfilling the tank and contamination are the usual causes of the foam. 

Foam in the oil can result in improper engine lubrication, which can cause overheating and friction issues with the engine’s parts. In this article, we’ll go over some specific causes of foam forming in the oil.

Causes for Foam in Oil

There are several potential causes of foam forming in the oil. Some of them are: 

Excessive oil

The engine oil may foam if the oil level is too high. This happens due to the oil coming into contact with the crankshaft when the oil level is too high. The crankshaft’s fast-moving rod constantly rotates into the oil, causing foam to form. 

It is advised not to fill the tank up past the maximum level. This is due to the possibility that the crank may churn or aerate the oil if the oil is overfilled in the sump. If the foam is not discolored, oil overfilling is likely the cause of its formation.

Oil Contamination

The engine oil may develop bubbles as a result of additives. Your oil may contain solvents or water contaminants that have been dissolved in it. This additive allows air bubbles to form in the engine oil as the car speeds up.

Additionally, these additives prevent the oil’s anti-foam additives from performing as intended. Solids and oxidizing additives can also produce froth.

Cold Oil

Likely, the oil will easily form air bubbles if you live in a cold climate. Usually, the formation of air bubbles in oil is normal, but they burst. However, if the oil is too cold, the bubble becomes trapped and cannot rise and separate. 

This air bubble caused the oil to froth up. As oil does not reach the temperature to pop the bubble, this foam can also develop if you take short trips more frequently.

Moisture in Oil

When this moisture and oil are combined, the oil may foam. Small amounts of water do not have significant effects, but excessive amounts will cause oil to become frothed. There are numerous reasons why moisture could enter the oil. It is often also known as condensation in the oil.

Usually, when the oil filler cap is loose, water vapor gets into the oil. Oil and water can also mix as a result of leaking gaskets. The likelihood that the foam is caused by leaking coolant or water in the oil increases if it is slightly lighter in color. A leaking head gasket likely is to blame for foaming if the substance is creamy or milky in oil color.

How to avoid foam in oil

Your engine may suffer serious harm from the foam in the oil. Therefore, it is advised that you completely drain the engine of the old oil. Next, The following considerations should be made before adding more oil:

  1. Verify that the oil level is between the minimum and maximum levels. Tank overfilling will result in the formation of froth in the oil.
  2. Use high-grade oil with suitable viscosity properties and defoaming additives for your engine.
  3. To prevent moisture from getting into the oil tank, ensure the oil filler cap and gasket are properly sealed.
  4. If you live in a cold climate, make sure you occasionally take a long car trip. Use a low-viscosity oil. Due to the thinner wall and easier bubble break, low-viscosity oil has a lower likelihood of foaming in cold areas.

FAQ’s on Foam in Engine Oil

If the oil contains tiny air bubbles or if the foam results from the cold oil engulfing the air particles. Make sure to drive for at least 30 minutes to allow the air bubble in the oil to burst and the oil to warm up.

However, it is advised that you wait to drive the car until the oil is changed with fresh oil if the cause of the foamy oil is a leaking head gasket or other additives. This is because foamy oil can result in improper engine lubrication, which can cause overheating and friction in engine components.

Fully synthetic oil is said to be more expensive and of higher quality than regular conventional oil. As a result, synthetic oil contains more anti-foam additives than regular oil. Because these anti-foam additives prevent the formation of air bubbles in the oil, the foam does not form as readily in synthetic oil.


To properly treat the oil foam, it is crucial to identify its cause. Oil will foam most frequently when there is moisture present, when anti-foam additives are ineffective, or when the oil level is excessive. Lack of lubrication in the engine from oil foam can lead to friction or overheating in the car. 

As a result, hire a mechanic to examine your engine for the root of the foaming thoroughly. Ensure that you add the new, fresh oil only after flushing out the previous foam-containing oil.

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