SO, WHAT’S THE DIFFERENCE?
Conventional oil is a lubricant byproduct of crude oil refinement and although it contains cleaning agents, its largely extracted from natural resources that later gets refined. Vehicles using conventional/ Semi Synthetic oil are recommended to perform an oil change every 4,000 miles.
Full Synthetic oil per the Castrol website it’s an engineered lubricant produced with a combination of chemically modified petroleum and other synthetic elements, this type of oil performs better under high heat conditions and lubricates key engine components better that conventional oil. Vehicles using Castrol GTX Magnatech or Castrol EDGE oil are recommended to perform an oil change every 8,000 miles.