Premium leaded gasoline, the old high-octane standby, is going the way of the dinosaur.

In many areas of Washington yesterday, you couldn't buy a drop of it.

"This is ridiculous," complained Jack Moore, a Reston resident, after the manager of a Gulf station there told him there was no premium for his MG Midget. Moore checked all over Reston for it, and ended up driving to nearby Herndon.

"We discontinued premium, there's more demand for the unleaded with the newer cars," explained Clifford Reedy, manager of the Gulf Station.

The nearby Memco station had also discontinued premium, and the nearby Exxon could get it but had decided against ordering the gasoline because demand was so low.

Roughly the same thing is happening throughout the Washington area and the nation. Because more and more cars made since 1975 need unleaded gasoline to comply with the Clean Air Act, oil companies have increased refinery output of unleaded gasoline at the expense of premium leaded.

At the same time, the old clunkers with their big high-compression engines -- the cars that need premium to function efficiently -- have been going to the junkyard. Demand for premium leaded dropped from 33 percent of gasoline demand a decade ago to only 7 percent today.

The problem is that when the percentage gets that low, the gasoline system no longer distributes it evenly. Jim Gleason, the manager of the Exxon station in Reston, explained it this way:

Only about 6 percent of the customers at Gleason's and at other Exxon stations wanted leaded premium, down from more than twice that figure a year ago.

With supplies of all grades tight because of the national gasoline shortage, Gleason is receiving only 82 percent of the gasoline he got two years ago and has to choose which grades -- regular, unleaded or premium -- he wants to offer.

"We just can please more people by getting regular and unleaded,' he said. "I think premium [leaded] is just about a thing of the past."

Gleason and other industry representatives suggested that motorists who can't find premium leaded can often switch to regular leaded or to unleaded gasoline without hurting their cars.

"I have an old Oldsmobile that I always ran on premium," Gleason said. "I started putting regular in it and, in fact, my mileage increased."

Many motorists favor premium gasoline because their engines run more smoothly on it, without "knocking" -- a pinging noise in the engine caused by burning the wrong type of gasoline.

Premium gasoline prevents knocking and is therefore said to have "high octane" -- simply a measure of the antiknock capability of a grade of gasoline.

According to the U.S. Environmental Protection Agency, regular gasoline -- whether leaded or unleaded -- has octane ratings between 91 and 94, while premium gasoline is rated between 95 and 96.

The antiknock properties of a gasoline can be increased by adding lead or by refining it more intensively. Lead is being eliminated for environmental reasons, and unleaded gas -- which represents about 40 percent of all gas sold -- requires extra supplies of scarce crude oil when it is refined. a

Because it takes so much crude oil to produce unleaded premium, some oil companies are balking at relieving the drought of premium leaded.

Of the six major oil companies that supply 80 percent of the gasoline in the Washington area, only Exxon, Sun and Texaco still offer leaded premium to their dealers -- and the dealers doo not have to offer premium to their customers if they do not want to.

Amoco, with 26 percent of the market here has for years offered unleaded regular and premium but never leaded premium. An Amoco spokesman said yesterday that stations are out of unleaded premium "at a few locations."

But Exxon, with 24 percent of the Washington market, still considers leaded premium to be one of its key products. A company spokesman said yesterday there are no plans yet to replace it with premium unleaded, although industry analysts said such a move is inevitable soon.

Gulf, with 13 percent of the market here, dropped premium leaded from its product line during the last month in the Washington area and plans to phase it out across the nation by March.

"We're considering marketing an unleaded premium but don't know when that would be available," said a Gulf spokesman in Houston yesterday.

Shell, with 6 percent of the market here, dropped its premium leaded nearly a year ago and replaced it with an unleaded grade of 91.7 octane that a Shell spokesman said was "premium" but which other industry analysts described as a "super regular."

Sun, with 5 percent of the Washington market, dropped its highest octane premium leaded last spring, but retained a premium leaded of slightly lower octane. A spokesman said yesterday that, too, will be phased out in 1980.

Texaco, also with 5 percent of the market here, still offers premium leaded to its retailers but a company spokesman said yesterday that half of them do not bother to stock it for their customers now.

Texaco has been running advertisements in The Washington Post saying that it has 600 stations offering gasohol -- the equivalent of premium unleaded -- but a spokesman said yesterday that none of these stations is in the Washington area. The question of whether Texaco will offer gasohol -- a mix of 10 percent alcohol with 90 percent unleaded gasoline -- here is being studied, the spokesman said.

In any case, the company has just about phased out the old premium unleaded, he said.

Mobil offers an unleaded premium, but its share of the market here is small.