Dexos oil is motor oil that is licensed by General Motors to carry the dexos specification. The dexos specification is awarded to oils that have passed a number of tests conducted by GM and that have paid for the dexos license.
The dexos specification is exclusive to General Motors, and any oil carrying the dexos logo is suitable for meeting GM warranty requirements. To meet the dexos requirements, an oil must typically be synthetic or a synthetic blend. GM stated that dexos was introduced to simplify oil selection and ensure increased fuel mileage. The American Petroleum Institute and the International Lubricant Standardization and Approval Committee have similar oil ratings.