Bob Williams of Hideaway Road in Fairfax County says he has a big problem.

He rents a house that was built in the 1950s, when oil cost 20 cents a gallon. "It's like trying to heat half of Fairfax to keep this house warm," he said with a laugh.

His solution to rising fuel oil bills was to join Buyers Up, a nonprofit consumer group that provides less expensive heating oil to its members in Virginia, Washington and Maryland through group buying. It operates from a second-story office just off Dupont Circle in the District, with a staff of six, a computer and endless volumes of oil industry publications.

Founded two years ago by consumer advocates Ralph Nader and Joan Claybrook, Buyers Up has enlisted nearly 5,000 customers in the Washington metropolitan area. In Virginia, it includes Alexandria and Arlington, Fairfax, Fauquier and Loudoun counties.

Williams reports "so far, no problems" using the service. With his high usage, the 6- to 10-cent-per-gallon saving that Buyers Up provides can mean a substantial savings over a winter.

Irene Wallace of Fort Worth Avenue in Alexandria heard of Buyers Up while watching Nader on a television show last year. "We are pleased," she said, citing a 19-cent-per-gallon reduction in her heating oil costs.

Buyers Up is not an oil company or distributor. It is a liaison, connecting consumers with participating oil companies, who then deliver oil at a price several cents per gallon below the market rate. Last year, Buyers Up users saved an average of $220 in heating oil costs, said Jason Adkins, 24-year-old director of the group.

The service is available to any area heating oil consumer. Buyers Up charges a membership price is $15 for houses, $25 for nonprofit operations and $35 for businesses. Low-income users pay a $5 membership fee.

A spot check of eight area distributors this month showed that prices ranged from $1.27 to $1.15 for a gallon of heating oil. The Buyers Up price was $1.05.

Energy consultant L.T. Via, who works with Tri-Continental, said that in a market such as Washington, where a few large heating oil companies have kept steady customers for years, it is difficult for a new company to gain a foothold.

For a small, relatively new (and in the case of Tri-Continental, minority-owned) business to elbow into the market, it must offer an appealing incentive, such as the Buyers Up price discount. The oil company trades a higher profit margin to gain customers. In Virginia, Gaddy Oil and Continental Petroleum participate in Buyers Up.

Since cutting down on how much oil a homeowner uses complements lower prices, Buyers Up has free planned energy conservation services for customers. Energy audits, which reveal deficiencies in house structures and furnaces that may allow heat to escape, will be offered free, on the condition that the customer follow up on the recommendations.

Simple adjustments that Buyers Up can arrange for homes such as fresh caulk around windows, weather strips on doors and effective dampers on chimneys keep houses substantially warmer, Adkins said.

As a nonprofit group, Buyers Up operates with a limited budget that precludes a glitzy advertising campaign. Staff members approach the public on a personal level, talking with churches, community groups, unions and neighborhood newspapers.

Adkins notes that Buyers Up is open to all heating oil users, and hopes more consumers will join it.

"People should wise up," he said. "Oil is oil and delivery is delivery."