A Core deposit is a form of deposit you pay until returning your old part. If you don't have the core at the time of purchase, you must pay the core charge. That charge is refunded to you when you return the core.
The low-viscosity, advanced full synthetic formulation can help to increase engine efficiency and improve fuel economy. These oils are engineered with a proprietary blend of high performance synthetic base oils, fortified with a precisely balanced component additive system. Mobil 1 Advanced Fuel Economy oils provide excellent overall lubrication and wear protection performance for many driving styles and conditions, from mild to severe.