The energy department is selling a little oil out of its strategic reserve, just to test the system. This demonstration of capability is essential, and long overdue. It's a small sale -- just over one million barrels, one-fifteenth of this country's daily consumption. Sales like this one need to be a regular and routine part of managing this crucially important resource.

The strategic petroleum reserve has been carefully built up by the Energy Department in gigantic underground caverns along the rim of the Gulf of Mexico. It was first conceived as a response to the shortages that this country suffered in the 1973-74 oil embargo by the Arab producers. The idea -- and it was a good one -- was to build a shock absorber against sudden disruptions in the foreign oil supply and, especially, to ensure that foreign producers could not threaten the United States.

Organizing the reserve was slow work, and the department was not able actually to begin filling it until late 1977. In 1979 the department installed high-speed pumps that could retrieve the oil in an emergency. But it never quite got around to demonstrating the administrative and physical capacity to take bids on the oil, sell it and deliver it to the refineries -- fast. That is the capability that the current exercise will test. Perhaps there will be a few hitches. That's why it's necessary to keep doing it and make the procedures completely familiar both to the department and to its industrial customers.

The country now has about $14 billion invested in those caverns -- 490 million barrels of oil, the equivalent of 100 days' imports. Since one conspicuous reason for that investment is to deter anyone who might hope to throw the American economy off balance by interfering with the flow of imports, it's essential to show that the reserve can be fed, rapidly and smoothly, into the distribution system.

This kind of sale from the reserve is like army maneuvers. The purpose is not only to keep the troops proficient, but to show that proficiency to anyone who might be watching.