Hi guys. im very noob about car. recently my preve cfe has become 3 years. but my mileage just 37,000 km. So i just go to sc and do the major service 60,000 km as suggested by the sa. change the cvt oil, spark plug and etc. All in about rm1200.

My question is, is it necessary to follow the car age instead of mileage for the service?

I think my previous spark plug still can be used, can i keep it in a long time and used it back? or just sell it as used one.