Has the Oil Emulsification Issue in Toyota Hybrids Been Resolved?
3 Answers
Toyota hybrid oil emulsification issue has not been resolved yet. Hazards of oil emulsification: Oil and water are incompatible, but under certain temperatures and specific conditions, they can mix and cause emulsification. Emulsified oil turns white. Since engine oil lubricates engine components, its performance significantly declines after emulsification, leading to severe engine wear and reduced engine lifespan. Therefore, oil emulsification is not a minor issue. Normal oil emulsification phenomenon: Sometimes, when the engine is turned off and cools down, air enters the valve chamber where the camshaft is located. Condensation of water vapor in the air can cause slight emulsification on the oil cap. The accumulation of emulsion on the oil filler cap is entirely different from the oil emulsification issue. This is a normal occurrence and does not fall under the category of oil emulsification problems.
Speaking of the oil emulsification issue in Toyota hybrid vehicles, I personally encountered this with my Camry Hybrid purchased a few years ago. In cold weather, I often noticed a white, milky substance on the oil cap. Toyota has made improvements in newer models post-2020, such as upgrading the engine control system to reduce low-speed operation during short trips and enhancing seals to prevent moisture ingress. Now, after driving my car for over a year, the emulsification issue hasn’t reappeared. For owners, it’s important to adhere to regular maintenance schedules and drive on highways more often to burn off moisture. Toyota’s after-sales service generally recommends checking and updating the software during oil changes. With this bug resolved, driving feels much more reliable.
In our auto repair shop, we've handled numerous cases of oil emulsification in Toyota hybrids. It's mainly caused by water vapor generated during low-temperature engine operation mixing with the engine oil. Toyota has optimized the hybrid system control logic and improved cylinder block and oil pan designs in subsequent versions, essentially eliminating the issue. There are far fewer reports of such problems from customers who bought new cars. For older models, avoiding frequent short-distance starts and warming up the engine regularly can prevent it. From a maintenance perspective, this issue has been completely resolved - I deal with various vehicle conditions daily and know this best.
