The refinery workers union let its contracts with the oil industry expire tonight without calling a strike, in hopes of getting an agreement that exceeds President Carter's seven percent anti-inflation wage guideline.

A. F. Grospiron, president of the Oil, Chemical and Atomic Workers, announced shortly after the union's East Coast contracts expired at midnight that the OCAW's 60,000 oil workers will be asked to continue working while its bargainers explore a late offer from Standard Oil of Indiana (Amoco).

He declined to reveal the content of the Amoco offer but said it had "some honorable content" meriting further consideration, indicating it goes beyond offers from other major companies that fell within the guidelines.

Amoco reportedly offered a 73-centper-hour increase amounting to roughly 8 percent for 1979, and left the wage increase for the second year of the contract to be negotiated at a later time. More money for medical benefits was also reported to be part of the Amoco proposal.

Several other major companies sweetened their offers late today by raising their proposed first-year wage increase to 8 percent but kept their second-year offer at 6 percent -- for an average 7 percent increase over two years.

Nothing that the oil industry bargaining is the first major test of the administration's three-month-old voluntary wage-price restraint program, Grospiron said it could affect all other workers in the country, nonunion as well as union, and vowed to "fight in any way we can."

While the union was not now calling a strike, Grospiron told reporters the possibility of a walkout remains "very real." He said he could not predict how long the union would work without a contract.

The union is in a weak position to strike because the nation's refineries are highly authomated and can be operated for an extended period by supervisory personnel. Working without a contract, but with the threat of a strike at any point hanging over the industry, is a tactic that this union has used before.

After announcing that the union members will continue working, Grospiron said the policy committee will meet Monday morning to pursue the Amoco proposal and any other company offers.

The union has consistently rejected offers that dovetail the guidelines, saying such a settlement would have no effect in curbing rising prices, and would fail to keep oil workers abreast of rising living costs. The union claims that labor costs amount to less than one panny in the cost of a gallon of gasoline.

While the inflationary impact of an oil workers' pay increase would be relatively small, the OCAW provides the kickoff round of bargaining for 1979 and hence the first major test of the administration's voluntary wage-price guidelines.

An administration official has described the oil industry bargaining as a "significant" but not "crucial" test of the guidelines. Bargaining for a new master freight agreement covering 300,000 Teamsters is regarded as a more important test, but it will not come until late March.

"We're locked into the guidelines... but there is flexibility in them," said one leading industry bargainer, citing as an example the administration's recent agreement to ignore the increased cost of maintaining existing health benefits.