How low can petroleum prices go? That has been the question of the year in Texas, America's leading oil state, and at Billy Jack Mason's Exxon station on the north side of Austin yesterday, the ultimate answer was at hand.

Unleaded sold for zero cents per gallon.

It was a one-day deal, to be sure, sponsored by a local country music station, but rarely has a gimmick revealed so much about human nature and economics.

Texas is reeling from one blow after another because of slumping oil prices. Just Wednesday, Phillips Petroleum Co. announced that it was laying off another 2,500 employes, and Standard Oil said it was cutting its exploration by half. Yet here in the capital of the energy state, when word spread that free gas was to be found, the populace, as expected, went bonkers.

Not even during the odd-even days of the gas shortages (when eligibility for fuel was determined by the last digit on a car's license plate) had Austin seen anything quite like this. It was the Texas Gas Rush.

By 9 a.m. the backup at Billy Jack Mason's stretched six miles down the access road parallel to Interstate 35. Some motorists had been waiting since 5:30. They had driven from as far away as Elgin and Bastrop and Waco, using half a tank of gas to get to the station for a free fill-up.

"Greed," said Marsha Glass, displaying remarkable skill at self-analysis when asked what compelled her to rise an hour early and get trapped in the incredible traffic jam. "This is what greed gets you."

Greed got Glass a little less than she had anticipated. Her car stalled at 8:30, and she had to search out a fellow Gas Rusher with jumper cables. By the time her car was restarted, Glass decided that she had to get back to work at the Texas School for the Blind. So much for the free gas.

Lisa Huber, an assistant manager at a hamburger palace, was more resolute than Glass but no luckier. She ran out of gas waiting in line. Her car was about a mile from Billy Jack's, so she trekked up the road, past hundreds of honking, sleeping, swearing, drinking, joking fellow travelers, finally arriving at the service station. They gave her a free gallon in a drum. Then she had to walk back to her car in the muggy, polluted morning air. What a bargain.

Michael Johnson drove 30 miles from his home town of Bastrop when he heard about the free gas at Billy Jack's. He said he learned a lot about people from waiting in the line since 6 a.m. "Some people damn near try to kill you to get in line. They do whatever it takes, then they flip you the finger," said Johnson, a cab driver. He said he felt sorry for the oil field workers who have been losing their jobs as the price plummets.

Would he be willing to pay more so they could keep their jobs?

Johnson laughed. "Jeez," he said. "Not really."

"The price of gas went up too much to begin with," said John Dominguez, lounging in his old Buick behind Johnson's pickup. "We're just getting it back. We're just getting a reimbursement here. That's how I look at it."

"Gas Wars! Gas Wars!" shouted Shane Danise, a painter, as he waited in line, his truck pushing an old clunker just ahead of him that had a gas gauge stuck "dead on E." Danise had never met the clunker's driver, Albert Rivera, but they had become buddies after three hours.

"How many times in your life do you get free gas? It's the opportunity of a lifetime," said Danise. "The way gas was going before, the oil companies were making too much money. I think around $20 a barrel would be about right. That would put the gas at 80 or 90 cents a gallon. With cheaper gas, I have more for food and clothes, and with my tight budget, that really helps."

A few cars down the line from Danise sat Richard Vomard, a fellow who sort of symbolizes the Texas paradox. His livelihood depends on high oil prices. He works for a company that manufactures weighing devices for oil rig companies. On the other hand, Vomard needs to save every cent he can. He drove one car to Billy Jack's and had his 17-year-old daughter drive the other.

Billy Jack Mason's Exxon station, the promised land, loomed on the top of a ridge. The greeting party at the station was led by Mrs. Billy Jack Mason herself, offering free coffee and doughnuts, and a beefy attendant who seemed to be eating one doughnut for every one he handed out. Austin policemen Tim Smith and Roger Floyd were also there, directing the flow of traffic and commenting on the passing scene.

"Ah," said Smith as he arrived. "I think I'm gonna write myself some tickets. Expired inspection stickers."

"Incredible," said Floyd. "All this for 15 gallons of gas. No way I'd do it. No way."

"Well, look at these people, Roger," Smith said. "We're looking here at your basic lower middle class. For free gas, if I was them, hell, I'd be in line, too. But not behind 500 million other guys. You don't see no high rollers here. The high rollers are downtown in their business offices."

"Yeah," said Floyd. "I guess these are the victims of Reaganomics."

Inside the station, resting on a stool, Billy Jack Mason, the proprietor, was giving lessons on creative capitalism. "The thing you gotta do is create a little action," said Mason. "That's what I'm doing here today. Create a little action. Action makes progress. Progress makes production. Now with the price of gas, that's another thing. That's overseas. Nothing we can do about that until the A-rabs get the prices right."