On the first holiday weekend of the summer driving season, gasoline stocks have dropped close to the minimum level the Department of Energy says is needed to avoid runouts and shortages.

But, barring a major political disruption in the oil-producing Mideast, no shortages are in store, according to oil industry economists and observers.

A dip in gasoline inventories to such a level a few years ago might have foreshadowed a long hot summer spent in gas lines. This year is different, for two reasons: demand is far lower, and refiners have additional capacity and crude oil available if more gasoline is needed.

"You could safely forecast there won't be any gas lines because basically there's no shortage of crude," said one oil industry official.

Even so, the direction stocks are taking has raised some concerns. One major oil company is allocating supplies, although still providing more gasoline than this time last year to its wholesale customers. Other companies are taking steps to prevent a run on their supplies by limiting deliveries to contracted-for amounts. Normally buyers are not limited by that amount.

"The situation in stocks appears to be paralleling many of the trends of 1978, which, of course, set the stage for the shortages of 1979," Rep. Richard L. Ottinger (D-N.Y.) wrote President Reagan earlier this month.

"With crude stocks significantly higher than that time, and demand reduced, these product stock levels may not be as perilously low as they appear. However, the trend is certainly alarming," he said.

Shortage or not, gasoline prices are going up and are expected to rise by 2 to 3 cents for the rest of the summer. At that level they still will be well below last year's prices. Prices are being boosted by increases in the price of crude and an attempt by refiners and retailers to make up recent losses, as well as by the level of gasoline stocks.

"Because there is a surplus of crude, this shouldn't be happening," said Ed Rothschild of the Citizen/Labor Energy Coalition. "I think we may see evidence of some shortages in some parts of the country."

But industry analysts say the facts don't suggest a serious problem.

"What's happening does not translate into any possible national shortage," according to Dan Lundberg, publisher of a newsletter on the U.S. gasoline market. "The idea that we could develop widespread outages of gasoline because of insufficient availability of supply is grotesque."

"Gasoline stocks are unusually low, but . . . can be increased. There is not a resource shortage," said John Lichtblau, president of the Petroleum Industry Research Foundation.

"I don't regard motor gasoline stocks as unreasonably low in regard to demand," said Edward Murphy, director of statistics for the American Petroleum Institute. "This summer in the peak driving season anticipated gasoline demand is expected to be 300,000 to 400,000 barrels a day less than in the lowest portion of the year in 1979," he said.

Besides declining, demand for gasoline no longer fluctuates seasonally as much as it once did, he said. The difference between demand in January and June has decreased markedly in the past few years. As a result, said Murphy, the need to build stocks for the summer has abated.

Stocks as of May 21 were 215.7 million barrels a day, hovering just above the 210 million barrels a day that DOE uses as its figure for minimum operating inventory. The figure was devised by the National Petroleum Council, an advisory group, in 1979 and has not be revised as demand has dropped.

With stocks at that level, the nation has a 31-day supply of gasoline--fairly normal, according to Murphy. At this time in 1980, with the glut building, there was a 38-day supply and, in 1981, it was 39. But supply had hovered near 31 days for previous years going back to 1975, according to Murphy.

Two major factors have reduced demand. One is lighter, more fuel-efficient cars. Even with drivers holding on to older cars longer, the old gas guzzlers are being replaced.

Still another factor is what Lundberg calls "driving by objective." Motorists are more likely to carefully plot their trips to make needed stops as efficiently as possible.

Demand appeared to jump earlier this year with a more rapid disappearance of motor gasoline from primary storage, according to industry economists. Primary storage is gasoline located at refineries, in pipelines and at other large terminals.

Gasoline inventories were already at low levels in primary storage. The fact that it costs so much money to hold product, combined with the fact that refiners have been losing money, provided an incentive to get rid of stocks on hand.

Then the same thing happened at the next level--gasoline stations, fuel oil dealers, electric utilities, commercial buildings and others. As gasoline prices dropped, there was little incentive to spend the money needed to store gasoline.

When prices began to turn around in early spring, the rules changed and a scramble to refill began.

There were reports that some major oil companies were allocating supply to dealers. A spokesman for Gulf Oil Corp. said that Gulf is allocating supplies to dealers, jobbers, commercial and industrial users. But, added Gerald S. Bradley, "It's not an allocation that an average motorist would notice."

Bradley said that the allocation allows dealers and others to take a maxiumum of 125 percent of the average amount that they took in the first quarter of the year. That amount allows them approximately 12 percent more gasoline than they took on average this time last year, he said.

Texaco and Shell were also said to be allocating supplies, but denied doing so.

A Texaco spokesman said wholesalers are getting their contractual allotments, but deliveries may be paced. In other words, if a wholesaler's allotment is 10,000 gallons a month, he will get that amount, but deliveries will be spread out rather than one delivery at the beginning of the month.

Shell spokesman Hugh Depland said Shell also is providing amounts specified in its contracts to jobbers (middlemen who supply some Shell stations and other stations). For the last half of May, jobbers have been told they can lift only 50 percent of their May allocation, unless they were below 50 percent in the first half.

"When the jobbers come to us and say fill up our tanks, if they all come at once all around the country, it depletes our inventory," he said. "That's what's going on and why we put a restriction on for month of May."

If more gasoline is needed, more can be produced. Crude production is slowing down but it is still in sufficient supply, according to most monitors. DOE says that refineries are producing at approximately 66.7 percent of capacity.

Although industry sources think the DOE figure is slightly lower than reality, there is still spare capacity. Since it is more costly to refineries, with high fixed costs, to operate at low levels, there also is an economic incentive for refiners to boost production if demand exists.