Motor oil can be segmented into four basic varieties—synthetic oil, synthetic blends, high mileage oil, and conventional oil.
Synthetic motor oil has gone through a chemically engineered process. Synthetic oil molecules are more uniform in shape with fewer impurities and better properties than conventional oil molecules. In general, synthetic oil has better extreme high temperature and low temperature performance. Synthetic oils are generally formulated with higher performing additives.
Synthetic blend motor oil uses a mixture of synthetic and conventional base oils for added resistance to oxidation (compared to conventional oil) and provide excellent low-temperature properties.
High-mileage motor oil is specially formulated for late model vehicles or newer vehicles with over 75,000 miles. High mileage motor oil, with its unique additives and formulation, helps to reduce oil burn-off, and helps prevent oil leaks that may occur in older engines.
Conventional motor oils can be formulated in a range of viscosity grades and quality levels. Conventional motor oil is recommended for drivers with simple engine designs and regular (as opposed to severe) driving styles.