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What Causes Engine Oil Emulsification, Forming the So-Called "Mayonnaise"?

Model: (Various brands) Various
Part: Engine oil

In this video, we can see what causes the oil in our vehicle to emulsify, forming the so-called "mayonnaise", a slimy whitish emulsion that, from its appearance, promises nothing good. The first reason for its formation is a blown head gasket, allowing coolant to mix with the oil, resulting in this unpleasant outcome; consequently, the coolant reservoir level drops, and you may find a similar emulsion there as well. The second reason is incorrect oil viscosity or using semi-synthetic (or mineral) oil instead of synthetic oil. If the oil has incorrect technical specifications, it creates excessive condensation, which, with engine movement, results in this sludge. The third reason is infrequent use of the vehicle: if you use the vehicle little and for short distances, this condensation will form even if the gasket and oil are perfect, causing the same problem and increasing the oil level. Remember, in any case, this emulsion is a warning of a very serious issue.

Updated on 2 September 2026 by ScegliAuto

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by ScegliAuto

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