Six weeks after California began the year's first odd-even gasoline sales system, the once excruciatingly long lines have all but disappeared from service stations.

State officials and spokesmen for the auto club here assert that the odd-even provision, along with regulations prohibiting the topping-off of tanks over half full, have helped the state cope with supplies of gasoline that are as much as 10 percent less than last year's.

"It helped us almost immediately," said Richard Maullin, chairman of the State Energy Commission."The first real effect of it was more psychological than anything else. It said the government was steping into a situation that to a man on the street seemed out of control. It's all been a way to restore order to a confusing situation."

Claifornia's odd-even system began May 8 in 15 of the state's 80 counties after two weeks of panic buying in late April and early May. It was in these 15 urban counties-which include more than 80 percent of the state's population-that the gasoline shortage first hit and hit hardest.

Mike Masinter, spokesman for the automobile club of Southern California, estimates that it took from 10 days to two weeks for the odd-even plan to take full effect. He said gas lines now are seen only on weekends and even those tend to be short.

"It's really worked fantastically. The odd-even works great," Masinter said. "It forced the conservation thing right into people's faces. It's almost liveable here now. You can even get gas on Sunday if you really need it."

Masinter and others point out, however, that odd-even does little more than regulate the shortages and cannot be expected to eliminate some of the harsher economic impacts of the gasoline crisis Most severely hurt, he said, are the tourist industries in such relatively remote places as Lake Tahoe, the central California coast and the Sierra Nevada mountain resorts that are more than a tank of gas away from a metropolitan area.

Requests for long trip planning at the Southern California auto clubs, according to Masinter, are down nearly 25 percent from last year's level. "People are taking shorter trips," he said "They now only take one that requires a single tank.They don't want to take the chance of not getting gas."

While the weekend gasoline situation has improved, Masinter adds, odd-even is unlikely to return the state to the halcyon days when gasoline was easily available on almost any major strip in the state. In Southern California according to the auto club, neary 18 percent of all gas stations were open last Sunday, compared to only 7 1/2 at the height of the crisis.

In the past, however, it is estimated that about half the stations usually were open on Sundays.

The weekend openings have been prompted both by strong state regulations requiring stations to be open at least one day during the weekend, and the reduction in late-week panic buying, according to energy commission chairman Maullin. Similarly the order has helped some stations stay open longer, some for more than six hours a day on weekends.