All of spark plugs were vailed white. this is the symptom of too high heat spec for cylinders. I checked the heat spec of them. These heat spec are BOSCH 7, but Genuine parts is NGK 7. Bosch 7 and NGK 7 are not same heat spec. BOSCH 7 is more heat than NGK 7. BOSCH 5 is same heat spec NGK 7. It may the cause of white vail of spark plugs and Oxygen sensor.