On Monday, the first federal holiday marking the birthday of Martin Luther King Jr., WWDC disc jockey Doug Tracht, otherwise known as "The Greaseman," suggested on the air that if the assassination of a black leader was cause for a day off, then killing "four more" would result in getting the rest of the week off.

Tracht, who has the second-largest audience in the morning in Washington, reportedly said immediately that he was "only kidding." Later, he returned to the station and made a formal apology on the air, which he repeated the next day. "What he said he shouldn't have said, and he thinks he shouldn't have said it," said WWDC President and General Manager Goff Lebhar yesterday.

The station management refused to provide the exact wording of Tracht's statement, and Lebhar said the station did not keep transcripts or tapes of its broadcasts. He said the station had received only two phone calls about the remark.

"I thought it over and thought it was the wrong thing to do," Tracht said yesterday. "I can't confirm or deny [the statement]. The station doesn't want me to talk about it." Tracht starts what Lebhar called a previously scheduled six-day vacation today.

Lebhar said he was satisfied with Tracht's two apologies and planned no disciplinary action. "I heard about the remark. I called him on the phone. He told me about the bit and I told him to make a U-turn and come back to apologize." Lebhar added, "I don't know what else he could do."

Tracht was hired in 1982 by the album-rock outlet of Capitol Broadcasting Co. to succeed Howard Stern, who also had a large following but whose material was viewed as offensive by many people. Stern, who was fired by WWDC, was subsequently fired from his next job in New York. Lebhar said yesterday Tracht doesn't generate as many complaints as did Stern.

Tracht, 35, a native of the Bronx, N.Y., has worked in Ithaca, N.Y., Hartford, Conn., and Jacksonville. He reportedly has a five-year, $1 million contract at WWDC.

Tracht specializes in long skits, delivered in a gravelly, menacing voice and backed up by colorful sound effects. His listeners number 63,000, according to the most recent Arbitron ratings. His audience has grown significantly from last year, and he has managed to cut into the 25-year leadership of WMAL-AM's Frank Harden and Jackson Weaver. Tracht is generally acknowledged to have a predominantly young, white male audience; 43,200 men over 18 are listening during any given 15-minute period, more than any other station at that time.

For three consecutive years, Tracht has been named "Best Radio Deejay" by The Washingtonian magazine.

At the same time, letters written to the Federal Communications Commission complaints branch about WWDC since 1983 have targeted Tracht for being "gross, disgusting and obscene" and "sexist, racist and vulgar," and for using "the public airwaves to spread prejudice."

"I am stunned that any one on the airwaves would discuss steamrolling blacks and Koreans to create blacktop highways with yellow stripes on them," said a letter dated Feb. 1, 1985, from a man in Vienna, who concluded "where is your social responsibility? . . . Greaseman is perpetuating -- even creating -- damaging and injurious stereotypes and must be stopped."

A letter written last October from a woman in Arlington detailed a story Tracht told about sex in a car. "It is implied that she performs oral sex on the young male driver . . . Perhaps this sort of 'humor' has its place in a strip joint, but I find it totally unacceptable for radio, where children of any age can and do readily tune in and listen." Another letter complained about "some very tasteless jokes" told by Tracht about acquired immune deficiency syndrome.

In this week's edition of The Business Review, a local newspaper, Lebhar is quoted as saying Tracht's skits haven't cost the station any sponsors. He says the most complaints he gets are from older women who consider Tracht a chauvinist. "I've never given it much thought, but I wouldn't stop my child from listening. There's really nothing in the show that sets a bad example, and in fact, some of it sets good examples for kids," Lebhar is quoted as saying.

In response to a letter about a sexual routine, an FCC official wrote, "Unless the content of a program can be clearly shown to be obscene or indecent, there is no recourse at the federal level in view of the no-censorship provisions of law. It has been our experience that most material complained of, as offensive as it may be, is not actionable."

Edythe Wise, chief of the complaints and investigations branch of the FCC, said the commission is "cautious and careful" about programming complaints. The FCC, she said, could only act on obscenity if a local court had determined what is obscene. The commission also gauges the offensiveness of a remark by the repetition of the statement and the time of day it was played.

"However reluctantly I would defend Greaseman's First Amendment right to say that, nothing in the FCC regulations prohibit that," said Andrew Schwartzman, executive director of Media Access Project, a telecommunications law firm. "The larger question is whether a broadcaster who permits such crass programming to continue and defends it because some people listen and they can fill commercials for it ought to be licensed in the first place."

Other broadcasters, most of whom did not hear the remark directly, expressed rage and disbelief. "My first reaction was outrage," said Alan Goodman, general manager of WAVA-FM. For "anyone who can purport to be a broadcaster with a following like he has, it is reprehensible. If one of my jocks did that, if I didn't fire him, I would suspend him. Greaseman is a good talent and so you wonder what was going on in his mind."