Primarily, motor oil is used to lubricate the engine, thereby reducing friction and wear of moving parts while cleaning the powerplant from sludge and varnish. In addition, motor oil improves sealing of piston rings while cooling down the engine by taking heat away from its moving parts.
Buying motor oil could be overwhelming, no thanks to the wide array of available products. Furthermore, using the wrong type of oil could prove to be a disaster to your engine. Thus, you have to choose right type of oil for your engine.
Basically, there are four types of motor oil: conventional (regular), synthetic, synthetic blend and high mileage motor oil. Since the type of motor oil that your engine needs depends on the on the age of your car and your driving activity, knowing the their characteristics would help you determine which would be the best for your ride.