What Causes White Foam in Motorcycle Engine Oil?

[StBrooke]

Motorcycle transmission oil with white foam may be a mixture of oil and water or other substances. Oil-water mixture scenario: In water-cooled systems, it could be due to coolant leaking into the oil. For air-cooled systems, check if the filler cap has poor sealing. Another possibility is water entering the oil during washing. Other substance mixture scenario: When lubricating oil comes into contact with air and is vigorously agitated during flow, air can become mixed into the oil, creating foam. If this foam isn't promptly eliminated, it can reduce the oil's cooling effectiveness, cause airlocks in pipelines, lead to insufficient lubrication, increase wear, result in oil tank overflow, and even cause oil pump cavitation.