THE SAUDIS' oil strategy is working. That is the meaning of the highly interesting turn downward this week in crude oil prices. For the past two years, Saudi Arabia has been determined to reestablish a unified OPEC price schedule based on its oil. The Saudis have steadily maintained a high rate of production, undercutting the high flyers -- from Libya to the Rocky Mountains -- who were charging walloping premiums. Slowly, implacably, the Saudis are asserting their power to flood the markets and force prices down to their level.

But no one can say how long this campaign will continue, or how low prices will go. The Saudis have repeatedly suggested that, having achieved OPEC price unity on their terms, they will initiate a policy of gradual but continual increases to compensate the sellers of oil for inflation and a little more. Perhaps oil will get slightly less expensive for a while. But it wouldn't be wise to count on that to last.

The Saudi strategy was working last summer, and prices were sinking, until September when the war broke out between Iran and Iraq. Prices then jerked upward in response to the abrupt cut in supplies. But the Saudis kept going, patiently, and now prices are coming down again.

The Saudis are using the oil weapon -- this time against the other producers rather than the consumers. Their strategy is clearly increasing tension within OPEC. However successful abroad, it also appears to be sharpening dissent within the kingdom -- among Arab nationalists who press for solidarity with other producers, among religious conservatives who resist the erosion of tradition by the inundation of foreign money, among technocrats who deplore the waste in the present surge of wealth. The dissent has not yet been sufficient to deflect the oil policy from its course, but the government cannot afford to ignore these forces indefinitely.

Saudi Arabia's production for nearly two years has been in the range of 10.3 million barrels a day -- which is to say, one-sixth of the entire world's oil production and more than that of any other country except the Soviet Union. It is five times the production of the countries that are now the next-largest producers in OPEC, Venezuela and Nigeria. The Saudis have said many times that they want to return to a production ceiling of 8.5 million barrels a day.

For Americans, the crucial lesson here is that the world supply of oil depends on all sorts of unpredictable events -- wars, revolutions, and Saudi policy decisions. World prices are now sinking because of high Saudi production, but also because of falling consumption in the industrial world. By using less oil, Americans have made an important contribution to to this decline, and, if they want to keep the trend going, they will keep finding more ways of using less oil.