As home heating oil prices continue to hover above $3 a gallon, homeowners who decided to pay upon delivery for their oil might wish they had locked in a lower price by signing up for a pre-buy program earlier this year.

“Pre-buy” refers to a customer’s decision either to agree to a fixed rate or to pay upfront for a year’s worth of oil.

At Griffin Oil in Levant, office manager Gayle Libby said she continues to receive calls from customers hoping they still might be able to get into a pre-buy program.

“That’s hindsight now,” Libby said. “Our pre-buy program ended in September.”

Most oil dealers close their pre-buy programs before the end of October. Griffin customers could have locked in a rate of $2.46 a gallon in the summer, while those who chose to pay upon delivery faced a $3.099 a gallon price on Friday. The difference amounts to $159.75 when filling a 250-gallon tank.

“So far, anyone that’s locked in has done well, or at least it sure looks like it at the moment,” said Tim Dysart, owner of Dysart’s Inc. in Hermon. Dysart’s has closed its pre-buy offerings for the year; the company advertised prices earlier this year as low as $2.399 a gallon.

This year, Dysart’s had fewer pre-buy customers because last winter those customers lost money when oil prices fell below fixed pre-buy prices. Instead, more customers decided to pay upon delivery this winter, Dysart said.

Despite a $3.59 a gallon pay-upon-delivery price on Friday, Dysart said he has not yet noticed a change in business.

Jamie Py, president of the Maine Oil Dealers Association, noted that prices could drop drastically at any time.

“A lot of people are saying there’s no fundamental reason for the market to be where it is, and the bottom could fall out,” he said.

Signing up for a pre-buy program is generally a good idea, Py said. In seven of the past 10 years, pre-buy programs have benefited consumers, and in two of the past 10 years, market prices dipped below pre-buy prices, Py said. Only one year saw the market remain at par with pre-buy prices, he said.

Heating oil prices have risen by up to 75 cents a gallon from last year, topping $3 a gallon for the first time in the state’s history. As in the past, average prices are lowest in southern Maine and highest in eastern Maine.

According to John Kerry, director of the state Office of Energy Independence and Security, there are several reasons heating oil has become so expensive. Among them are a rise in demand for oil in China and India, a weakened U.S. dollar, and artificially high bidding prices from traders and analysts on Wall Street and in other large financial centers around the world, he said.

Most Maine oil comes from the North Sea, the Middle East and Venezuela and is refined by Irving Oil in New Brunswick, Kerry said. As of Friday afternoon, light crude oil was $96.11 a barrel on the New York Mercantile Exchange.

Kerry advised consumers not to assume Maine fuel companies are inflating prices.

“I don’t think that’s happening at all. I believe that Maine oil dealers are very honorable and hardworking,” Kerry said.

With 80 percent of Maine homes heated by No. 2 oil or kerosene, Maine has the highest per capita number of homes that depend on such heating methods in the country, Kerry said. Relatively few homes in Maine depend on heat generated by wood, propane or electricity, he said.

Conservation and alternative energy sources are the best answer to rising oil prices, Kerry said.

“We have to move from a fossil fuel culture to a biofuel, biogas, ethanol culture,” Kerry said. “It’s a matter of having the will and the resources to follow through with it. This is a crisis, but I don’t believe it’s going away. Prices will drop, but they’ll only drop so far.”

Food and gasoline prices also are rising as a result of higher oil costs. University of Maine economics professor Adrienne Kearney said the Federal Reserve is watching for inflation, but so far reports growth in the production of U.S. goods and a moderate inflation rate of 2 percent. Food and energy costs are not included in inflation calculations because they are so volatile, Kearney said.

“We’re less dependent than we were on oil before,” Kearney said, comparing current oil dependency in the United States now and in the 1970s.

About 50,000 families in Maine rely on the federal Low-Income Home Energy Assistance Program to subsidize heating costs. The Maine State Housing Authority requires oil dealers participating in the LIHEAP program to provide an extra discount to LIHEAP customers to stretch their dollars.

The state has joined U.S. Sens. Susan Collins and Olympia Snowe in requesting $5.1 billion in nationwide funding for LIHEAP in the 2009 federal budget. In 2007, LIHEAP appropriations totaled $2.2 billion, $1 billion less than the program’s peak $3.2 billion funding in 2006.

The state’s Keep ME Warm program offers kits to help weatherproof homes in an effort to reduce drafts and heating costs. Information about LIHEAP and Keep ME Warm can be obtained by calling the state’s health and social services hot line, 211.