As a chronicler of the nation's service-station industry, Dan Lundberg might have enjoyed the idea of two businesses fighting it out over the same turf -- just like gas stations on the same block engaged in a price war.

But in this case, the combatants are Lundberg's children. And the turf is the dwindling market for information and consulting services for the nation's gasoline retailing industry, a market Dan Lundberg created virtually from scratch.

A year after their father's death, Jan and Trilby Lundberg are running separate newsletters using the family name, which in the oil industry is virtually synonymous with gasoline pricing and marketing news.

Jan Lundberg, who recently began publishing the monthly Lundberg Report out of Fredericksburg, says he is not out to compete with sister Trilby, who continues to publish the original Lundberg Letter in Los Angeles. Trilby won't comment on her brother's venture, or on why he suddenly left the family business after their father's death.

But industry sources and associates of the two say the competing newsletters are the outgrowth of a long-simmering family feud exacerbated by Dan Lundberg's death.

"This has been kind of a shooting war between Jan and Trilby," said one person familiar with the situation.

"There's been a terrible sibling rivalry," said one family associate. "They fought a lot."

And some in the industry question whether there is room for another gasoline marketing newsletter, particularly with oil prices low and the industry in a depressed state. "The last thing we need in the petroleum industry, in the marketing business, is another newsletter," said Dick Shaner, editor of National Petroleum News, a monthly that covers the oil industry. "The market shrank, that's all."

Still, Jan Lundberg believes his new publication will offer something different from the Lundberg Letter. He hopes that it will cover gasoline-marketing subjects far removed from basic pricing. And although he plans to emulate the Lundberg Letter's survey of gas stations, he said his studies will move beyond prices to focus on marketing trends, such as the proliferation of "C-stores," or gas stations that sell a variety of food and sundries.

"I'm not so much into the pricing. My company is into marketing research questionnaires," he said. "What I'm going to do is to try to do some unique articles and surveys that will have some bite to them and some humor even."

For years, the Lundberg Letter has been one of the most important journals of the petroleum industry. Tracking gasoline prices through a fantastically complicated system in which thousands of gasoline stations were surveyed each week by stringers paid $1 a station, it became known as the most accurate source of pricing information in the business. If the Lundberg Letter said the average retail price of regular unleaded gasoline in Denver, say, was $1.15 1/2 a gallon, it probably was.

Widely quoted in the media during the energy crises of the 1970s, the Lundberg Letter helped make Dan Lundberg something of a celebrity. The loquacious, colorful Lundberg, who resembled Col. Harlan Sanders of Kentucky Fried Chicken fame, appeared frequently on the nightly television news and in newspaper and magazine articles to explain the latest move in the price of gasoline.

The Lundberg Letter was always a family business. At various times, all five of Lundberg's children worked for the publication, and at the time of his father's death, Jan Lundberg was the editor. But sources say Dan Lundberg never made clear plans for a successor. "Jan thought that he was going to get the ... top job," said a former employe of the Lundberg Letter. "He said that's what Dan's intention was. However, it was not in writing."

Sources say Trilby Lundberg, a concert pianist who had been publishing a spinoff newsletter called Energy Detente, moved back into the family business after her father's death. Shortly afterward, her brother and several key employes left.

The former employe said Jan Lundberg wanted virtually exclusive control of the operation, and the rest of the family balked. "Jan could have hung in there if he hadn't wanted the whole ball game," the former employe said. "He wanted all the marbles and he couldn't get all the marbles."

Neither Trilby nor Jan Lundberg would talk about what happened. But Jan said, "The company did change management, and I wouldn't have liked to stay in L.A. forever. It was just a good move personally" to leave.

Jan Lundberg moved to Fredericksburg early this year and began putting together a consulting and newsletter business. He says he chose Fredericksburg because of its proximity to Washington and its marked difference from Los Angeles. "I can walk to my office, I can walk to nice restaurants," he said. "Down here, I've got a good labor force that will work for less money because they don't have to hack I-95 or the Beltway."

Lundberg has hired a half-dozen people to staff the office, as well as several part-timers and dozens of stringers around the nation to do surveying work. Several of the part-timers and stringers are former Lundberg Letter employes, including former editors Mark Emond and George Baker.

One of Lundberg Reports' most valuable assets is the Lundberg name, which it won permission to use after what sources said were difficult negotiations between Jan and other family members. Jan Lundberg, however, said of the agreement: "It was one of those things I suppose a family does for itself -- sharing what it is that we have together."

The Lundberg name, he said, helps open doors for the new publication. "Our first foot in the door is our ability to get the information we seek, and that's why it's fortunate to have the name that my father started," he said. "A lot of people have heard the name Lundberg, even outside the oil industry, so when you go into a station -- unless the person who's running the station just came in from Vietnam -- they've heard of you."

So far, he said, he has not encountered any confusion within the oil industry over the two similarly named publications. Advertisements in trade publications for the Lundberg Report stress that it is not related to the Lundberg Letter, and Jan said, "My friends and contacts know where I am, and know there's no connection." And when asked about her brother's new company, Trilby Lundberg said, "It certainly isn't something that has to do with us."

Jan Lundberg does not rule out the possibility that the two branches of the family one day will rejoin forces. For the time being, however, he said, "They have the basic operation that my father set up over there, but I think it's better this way.