Synthetic blend oil improves oil viscosity versus traditional mineral based oils. It offers better protection of internal pump parts by reducing wear and friction. Synthetic blend oil extends the air compressor pump life, especially during cold weather use. A detergent type oil (used in car engines) suspends the contaminates and particles which are then removed by the oil filter, applications without oil filters (such as air compressors) should use non-detergent oil so the contaminates and particles settle to the bottom TERMS OF SALE: If, after receiving this item you discover that it was not the one you wanted, simply return it for a full refund within 30 days. Refund is void if you have installed, used or damaged the item in any way. Item must be returned with its original box, packing m.