WHEN GASOLINE and oil prices shot upward this week, they raised all the old questions about the United States' ability to protect itself from these disruptions. What has the country learned from the last two oil crises, each of which pitched it into a severe recession? Has it developed any weapons of economic self-defense?

The country is better prepared today for a major emergency like a sudden drastic shortage. It now has nearly 600 million barrels of crude oil stored in underground caverns. If prices were to stay high this month, sustained only by panicky rumors and profiteering, the administration would be right to start pumping from the reserve long enough to punish the speculators. But, valuable though it certainly is, the reserve can provide only short-term emergency help to a country that currently imports 8 million barrels a day -- more than half of its total consumption.

Beyond that the United States needs to take seriously the need, first of all, to conserve and, second, to shift away from its absolute dependence on enormous volumes of oil. It was making steady progress in both in the early 1980s, when oil was expensive. But when the price dropped in 1986, a lot of Americans began to forget the gasoline lines, the inflation and the recessions. Progress toward greater fuel efficiency waned in industry and throughout the economy. People began buying big cars again, enthusiastically abetted by the American manufacturers who, 17 years after the first oil crisis, are still unable to match the imports in fuel mileage. There probably won't be gasoline lines this summer. But if there were, who would be to blame -- the turbulent Middle Easterners or Americans who refused to protect themselves against obviously recurrent shortfalls in a fragile supply system?

A sharp drop in oil prices can be almost as dangerous as a sharp rise, for the drop makes people careless. Industrial customers who had switched to natural gas switched back to oil because it was a little cheaper. Interest and investment in solar power dropped off.

With a little luck, the world's oil price this year can be kept from flying as high as it did in the early 1980s. But it's not likely to return to the low levels of the past four years. That's just as well. Nothing has happened in the past week to make you think that the Persian Gulf region -- the source of one-fourth of the world's oil supply -- is getting more peaceful or stable. Consumers need a gentle reminder that, in their own interest, they need to be more careful -- should you say, more conservative? -- in using oil. That's another reason to keep the pressure on everybody with a steadily rising gasoline tax.