"我曾就機油使用壽命專門谘詢過美孚,答複是所有的美孚機油(普通,半合成與全合成)不開罐的貯藏壽命是十年,開罐後為一年."
I believe they are talking about the oil not in use but just sits then for a year.
"全合成機油的優點是低溫流動性和高溫抗氧化性能"
This is why fully synthestic oil lasts longer since it resists heat-induced oxidation better.
"也就是說在可以選擇 也可以不選擇使用合成機油時,使用合成機油在換油間隔上沒有區別。"
Don't understand the logic based on the above statements.