A lot of people are misinformed about thermostats and antifreeze. some people think permanent anti-freeze is just that -- it'll last forever. Others think that you should remove the antifreeze during the summer and run only water in the cooling system for more cooling.

And there are those who think you should remove the thermostat during the summer months for better cooling. Others think you should leave the thermostat in year-round, but should run a "colder" one in the summer than in the winter.

What should you do about the thermostat and antifreeze in your car? to answer that, let's take a look at what the cooling system is and how it works. This way you'll not only know the correct procedure, but have a better understanding of why it's correct.

Your car's engine produces power by the rapid burning of the fuel-air mix that is inducted into its cylinders. A piston in each cylincer compresses the fuel and air mixture, the spark plug ignites it with a spark, and the rapidly burning gases expand, forcing the piston down in its cylinder. Thus the power is produced which turns the drive wheels of the car.

The combination of the volatile fuel-air mixture produces tremendous heat. That's where the cooling system comes in. It dissipates much, of this heat. If it didn't, the pistons could quickly "seize" in their cylinders, the engine would stop running, and severe engine damage could occur.

Basically what the cooling system consists of is a series of passages that surround each cylinder. These passages and the radiator are filled with coolant. Much of the heat generated by the combustion process is transmitted to the coolant.

The water pump circulates the coolant through the radiator. The air being forced through the radiator (by the fan and by the car itself when it is moving forward) cools the coolant, which is circulated back into the engine by the water pump to remove more heat.

Now when the engine is cold, for best drivability, you don't want the coolant to circulate through the radiator. That's where the thermostat comes in. It is shut when the engine is cold, keeping the coolant inside the engine from circulating.

When the engine and coolant warm up, the thermostat opens, allowing the water pump to force the coolant through the radiator and back into the engine. Through experience and testing, the car manufacturers have installed a thermostat in each engine that best suits its needs. It opens and closes at the proper time, keeping the engine at an operating temperature that provides optimum performance for that engine.

What happens when you remove the thermostat? Not only does it take the engine longer to warm up, the engine in fact may never reach its proper operating temperature. Coolant is constantly circulating through the radiator, taking heat away from the engine when it shouldn't be.

For best engine performance, the thermostat should be left in the engine, and it should be the one that the maker put in the car. If it must be replaced, it should be replaced with one that has an identical operating range (some thermostats open at a lower temperature than others).

What about antifreeze? So-called "permanent" antifreeze is not permanent. The coolant (antifreeze and water) gets dirty, and the antifreeze "wears out." tCoolant should be drained every two years, and fresh water and new antifreeze added. Hoses and belts should be replaced at this time also.

Nor should you run straight water during the summer months. A mixture of water and antifreeze offers more cooling than water alone.

For best engine performance, and optimum cooling, your car's cooling system should be run as the maker intended -- with the recommended thermostat installed (the same one, year-round), and a mixture of antifreeze and coolant in the cooling system.