Imagine a single action that could end the West's dependence on Middle East oil, shatter OPEC and drive oil prices below $10 a barrel.

A daydream? No, all that is required is to equip all the cars and trucks on the road today to run on natural gas.To a great extent, this is what British Columbia did after the last oil crisis in 1979. Subsidies were introduced to encourage owners of fleets and private cars to add special tanks so that their cars could - at the flip of a dashboard switch - burn either gasoline or natural gas.

Now a network of 50 refueling stations serves fleet vehicles and individual owners. Owners of converted automobiles seldom use gasoline except as a reserve.

Natural gas has a high octane rating (130) and costs 50 cents to 80 cents per gallon equivalent. It is also plentiful, clean and easily distributed and is much safer than gasoline.

Compared with gasoline, it produces lower levels of nitrogen oxides and carbon monoxide and enormously lower levels of smog-causing hydrocarbons.

Standard gasoline engines can run on natural gas without modification although cars must be modified with a natural gas fuel tank. The gaseous fuel prolongs the life of engines, spark plugs and lubricating oil. As a result, 500,000-mile engine life is not atypical.

Technically, converting vehicles from gasoline to natural gas is easy. For roughly the cost of our current military operations in the Middle East we could convert about a million vehicles a month.

The advantages of using natural gas go far beyond economics. It would end a monumental waste of resources.

Known reserves of natural gas far exceed those of oil. Canada's are sufficient to serve North America's needs past the middle of the next century.

Unlike oil, natural gas is a renewable resource. Nature makes it from rotting vegetation. Biomass is therefore a huge and renewable source of supply. In fact, we could supply all our current needs simply from the gas produced by rotting vegetation and garbage dumps.

With all this going for it, why hasn't natural gas supplanted gasoline?

For one thing, natural-gas tanks hold less fuel, limiting the range for most cars to about two-thirds that of a full tank of gasoline. This means more frequent fill-ups and the necessity to be near a refueling station.

But the principal barrier to complete conversion is the large one-time expense of around $1,500, which can be recovered through lower fuel and maintenance costs.

The expense of conversion, doubts about price and spotty availability are enough to frighten off all but the hardiest souls.

The place to start is with urban fleets. Natural gas is such a bargain for them that subsidies should not be needed. Indeed, major delivery companies, such as Federal Express and United Parcel Service, have already begun converting on their own.

Once most of the nation's fleets are using natural gas private fueling stations will have more of an incentive to sell the fuel.

Natural gas should not be looked upon as a temporary substitute for gasoline. It is a superb fuel that we should use irrespective of instability in the Middle East.