Prolong Engine Treatment is quick and easy to use, just pour it right into the engine crankcase. For first use in a 4 to 5 quart crankcase, pour in the full contents of a 12 oz. Prolong Engine Treatment bottle. You can do this as part of or in between oil changes. Then use the 8 oz. Prolong Engine Treatment Booster for follow-up applications when the motor oil is changed. The Booster size, with the same superior formula, renews Prolong protection to the maximum level. It is recommended that the Booster be used at each oil change, definitely within every six months or 6,000 miles. The vehicle manufacturer’s recommended service schedule should always be followed.
For other crankcase capacities or engine applications, use Prolong Engine Treatment at 10% of the volume of oil.