Dozens of service station operators came here today to denounce what they perceive as the evils of their business: the new gas-and-go stations and the major oil companies that run them.

The operators, wearing work pants, caps monogrammed with the symbols of the companies whose gas they sell, and occasionally in faded, oil-stained shirts, testified in favor of five bills that would protect them against competition with the gas-and-go stations and give them added leverage in their ongoing battle with the oil companies.

The oil companies, which run many of the gas-and-go outlets, responded with arguments about the desirability of competition and free enterprise.

All of the bills under discussion are sponsored by Sen. C. Lawrence Wiser (D-Montgomery), who said he became interested in the plight of service station dealers because the balance of power between them and oil companies was too greatly in favor of the big companies for his taste.

One of the bills would forbid the conversion of full-service gas stations to gas-only stations for a period of two years. Service station operators feel they are being squeezed out of business by the gas-only gas-and-go stations, which can offer gas for between 3 cents and 6 cents less that the maximum full-service dealers can charge.

The gas station dealers couched their arguments for the bill in terms of the reduced repair services available to consumers from gas-only stations.

"During the recent cold-snap . . . the demand for emergency automobile service completely swamped existing repair facilities throughout Maryland," said Vic Rasheed, head of the Greater Washington-Maryland Service Station Association.

"Many of the dealers who a year ago could have helped handle the flood of calls for service could not respond," Rasheed said. "They are out of business. Their former service stations are now company-operated gasoline-only outlets with the repair bays boarded up, or the stations have been torn down and replaced with a cubicle and three pump-islands."

Paul Collier, eastern region vice president of Amoco Oil Co., responded that the bill "strikes at the very heart of self-service gasoline marketing, an efficient marketing technique that exerts downward pressure on the retail price of a gallon of gasoline."

The bill also is unconstitutional, Collier contended, because it would force property owners to "keep their investments tied up" in service bays, and afford special treatment to those who already own gas-and-go stations.

Collier offered statistics that demonstrated gas-and-go stations are increasing at a phenomenal rate, in May, 1975, he said, 9 per cent of the gas stations in Maryland were gas-and-go, today, 27 per cent are gas-and-go, he said. Nationally, he said, gas-and-go stations constitute 30.4 per cent of the market, more than twice their share 18 months ago.

A major battle between operators and the oil companies developed over a bill that would require oil companies that own their own retail gasoline outlets to sell gas to their dealers for at least 4 cents less than the price they charge the public in their retail outlets.