This lubricant is designed to be used to prevent rust in radiators of early cars with no thermostat. Early cars do not have a pressurized cooling system and, therefore, should not be using antifreeze. When antifreeze is used in cooling systems without thermostats, foaming of the antifreeze will occur. This will push out through the radiator cap and appear that the radiator is running hot, even when it is normal. Because this is a water soluble oil, it will prevent rust and corrosion in your early engine cooling system. In cold weather when freezing is a danger, the radiator should be drained and left dry or use anti-freeze during the winter months to prevent damage. *NOTE: LIQUIDS AND FLAMMABLES CAN NOT BE SHIPPED VIA AIR. NO OVERSEAS SHIPMENTS ONTHIS ITEM, GROUND FREIGHT FOR CONTINENTAL U.S. ORDERS ONLY.