回复：回复：回复：回复：机油哪里去了? “车有三谬，先说其一：合成机油。”

Agree 普通车在常规保养和驾驶情况下不时必须使用合成机油.  But the major reason we need to change oil is because of (per)oxidation/degradation and thus the oil loses it's lubricating property.  Since synthetic resists heat-induced oxidation then why can not we change it less often?  Synthestic one is advertized as lasting longer.  I know regular oil needs to be changed every 3-5 K is an overkill.  Synthetic is uaully changed every 10-15 K.  Since Volvo requires change of regular oil every 10K already, which is probably why they do not recommend a change more than 10K.  I am also surprised that Volvo asks change fo regular oil every 10K but synthetic every 5K (I may understand wrong, you are talking about regular oil every 5K?).  I am not auguing but just want to confirm since the statements are not consistent and do not makes sense to me.