While it may be fairly routine to drain your antifreeze when installing or removing your snow tires, authorities now say this practice deserves some rethinking.

Cost to you and the environment is causing experts now to take a second look at this annual draining ritual, said a Utah State University machinery expert.During the past decade, the country has experienced antifreeze shortages. Along with the shortages, the price for engine coolant has increased. Environmental concerns have also been raised, said Darwin Jolley, USU Extension agricultural engineering and machinery specialist.

He said manufacturers are taking a closer look at their antifreeze draining recommendations. Most have now extended this recommendation to two years, provided a coolant conditioner is added.

This does not mean, however, that the engine cooling system can be ignored. To maintain the cooling system at maximum efficiency, Jolley said some attention must be given periodically.

Today more power is being demanded of smaller engines. Turbochargers, intercoolers, air conditioners and high capacity oil coolers for engine oil and hydraulic systems have added to this problem, he said.

"All of these factors sort of ganged up on the engine cooling system," he said. "As a result, cooling systems have been made more efficient."

This new efficiency can be viewed as an ecological favor when it comes to draining the coolant. With less draining required, less coolant is being released into the environment, he said.

Leona K. Hawks, USU Extension housing and equipment specialist, said antifreeze, or ethylene glycol, is classified as a toxic substance - poisonous to humans and animals. Disposed of improperly, antifreeze can present an environemntal hazard by polluting ground, surface and drinking water supplies.

Not only does it pose a threat to the environment, when improperly disposed, it is also a human hazard - particularly to children - when improperly stored, she said.

It is not uncommon for people to store the fluid in old soda bottles. Children, believing it to be harmless, may drink it. To make matters worse, the fluid has a naturally sweet flavor to it, she said.

Hawks said antifreeze should be stored in its original container.

When disposing of it, she said the best thing to do is take it to a reclamation center or household hazardous collection site. If there isn't one in your community, hold on to it until you visit a community where there is one.

There are such centers in the Salt Lake area, as well as in Ogden and Provo, said Ted Diamant, solid hazardous waste specialist for Salt Lake County.

He said if your community does not have a recycling center, check with service station owners and automotive parts dealers to see if they would be willing to take your used antifreeze.

As a last resort, he said household quantities of antifreeze can be washed down the sink or toilet. The key is to flush it down with plenty of water.

Antifreeze should not be disposed of by throwing it in the trash or pouring it down a storm drain or gutter where it could flow directly into a waterway. Neither should it be poured into a septic system where it could kill bacteria and enzymes, he said.

In an attempt to minimize the amount of draining necessary, Jolley said at least one manufacturer, John Deere, has started a new program of antifreeze analysis.

The program allows customers to purchase sample kits from their dealers. A coolant sample can be drawn and sent in for analysis, he said.

Recommendations are then made as to the types of additives and the amounts needed to extend the life of the coolant for two years or longer, he said.