SmokeLess for a standard used car with a worn engine that smokes heavily. Designed to bring new life performance and protection to an aging worn engine. Manufactured from the finest ingredients to stop oil smoking to reduce emissions to give a cleaner more environment-friendly easier-to-sell vehicle. Results speak for themselves FHS SmokeLess car oil has a 99.9% success rate of greatly reducing the smoke or stopping it all together. You need at least enough for an oil change. 5 to 8 quarts for most cars. If you re not sure how much your car takes consult your owners manual. Average for most cars: 4 cylinder – 5 quarts 6 cylinder – 6 quarts 8 cylinder – 5 to 8 quarts depending on the size of the engine.