Quaker State Ultimate Durability 5W-50 Full Synthetic Motor Oil - 1 Quart (Pack of 6) Quaker State Ultimate Durability is our most powerful formulation, providing extreme engine performance and protection against deposits, which allows your engine to operate at maximum horsepower (1) Our full synthetic motor oil provides extreme temperature protection, delivering superior lubrication flow and pumpability at high and low temperatures (1) Excellent protection against the formation of sludge and other harmful deposits (1) No synthetic motor oil provides better wear protection (2) GM's dexos1 approved, compatible with biofuels ranging from E10 to E85, and suitable for hybrid vehicles