VR-12 Radiator Cooling System Protection - 4 Pack 1 bottle treats up to 3 gallons of any fluids. Organic & Biodegradable, Improve heat transfer, lowers temperature. Improves gas mileage and extends the life of your vehicle. Recommended maintenance: use 1 bottle every 5,000 miles or every 3 months. Compatible with all vehicle's coolants - Antifreeze energizer and cooling system booster.