An engine cooling system is an important component when a internal combustion engines used in vehicles. Early VW engines, particularly the early incarnations of the iconic VW Beetle, used an air-cooled system. In a nutshell, the system works by dissipating thermal energy into the air directly. However, after the second World War, most VW vehicles have adapted liquid-cooled principle and continue to do so at present. This is due to the fact that air-cooled engines have fallen out of favor for most car manufacturers, because minimizing emissions and engine noise has proven to be too difficult in air-cooled system. Air-cooling is still used in airplane engines, however, wherein the disadvantages are not that noticeable. The difference between the two applications goes beyond the medium in which heat is dispersed. In fact, the liquid-cooled principles borrows an application from its air-cooled counterpart. Liquid-cooled engines of VW vehicles use coolants (commonly a mixture of water and antifreeze, but other liquids have been known to be used), air is still needed in the process to cool the liquid itself. Another main difference is in the weight, with VW radiators, as well as other radiators of different makes for that matter, liquid-cooled engines are a lot heavier compared to air-cooled engines. One the other hand, the liquid-cooled principle has noticeably higher specific heat capacity, density and thermal conductivity. This is due to the fact that liquid, particularly water, can transfer heat farther and with less volumetric flow. At the heart of liquid-cooled vehicles is the radiator, which are obviously absent in air-cooled vehicles who use metal fins covering the outside of the engine's cylinder to increase the surface are for air to flow through. Radiators, typically located behind the car's grill, acts as heat exchanger and is connected to channels that traverse through the cylinder head and the engine. A device called the thermostat allows the coolant to circulate at a certain temperature by opening valves that releases the heated liquid to the radiator. At this point in time, the heat in the liquid is spread out via the air drawn in by the forward motion of the vehicle, augmented by a fan. It is important to note that VW radiators vary in size, this all depends on the model and size of the engine and vehicle, which in turn affects the ability of the radiator to handle extreme conditions that will the engine in question will undergo. This does not however, mean that the radiator is exempt from damage over time or use. Coolant leaking can cause the cooling system to be less effective or fail entirely. As with any other car component, proper maintenance and care is highly encouraged, as overheating problems can cause more damage to the engine itself, prompting for a more expensive endeavor. At the event of the worse case scenario, VW radiators are readily available in various shops that specialize in VW vehicles. The world wide web has also become a reliable source for such transactions, with the added security brought about by latest technologies. Either way, the necessity far outweighs economy when considering radiator replacements.