A small Jewish day school in San Francisco is expanding, but not without a fight between two Chassidic groups.

On one side is Rabbi Bentzion Pil, who has reaped national press coverage and government scrutiny for his controversial used-car donation program.

On the other side is Chabad, the international organization of Lubavitch Chassidim — some of whose members revere their deceased leader, Rebbe Menachem Mendel Schneerson, as the Messiah.

At issue is Schneerson’s name and whether Pil, who does not work for Chabad, can name his elementary school for the rebbe.

“You have nothing to do with Chabad Lubavitch…and most important — you have nothing to do with the Rebbe,” stated an Aug. 5 letter to Pil from Chabad West Coast director Rabbi Boruch Shlomo Eliyahu Cunin. “Thank you, and I hope that this notice to you in writing will put an end to the sacrilegious use of the Rebbe’s name on your institution.”

The letter, distributed to Chabad officials across the country, was the first missive ever sent out regarding the use of the rebbe’s name, Cunin said.

Known as the Beth Aharon School since it was founded in 1983, the institute was quietly renamed the Schneerson Hebrew Day School in January — though the former name continued to be used in public until recently.

Cunin, who did not find out about the name change until about a month ago by word of mouth, first telephoned and then wrote Pil expressing his opposition to the move.

“No one has the right to use the rebbe’s name without the official approval of Chabad,” Cunin said in a telephone interview from Chabad’s West Coast headquarters in Westwood.

Pil, however, said he has no plans to again change the name of the school, which he asserted was founded with the rebbe’s blessing.

“We did this to respect the rebbe, to give him a tribute…We love the rebbe,” Pil said in a telephone interview Tuesday from New York before visiting Schneerson’s grave. “The rebbe is the leader of all Jews…To say the rebbe belongs just to the Chabad organization is just ridiculous.”

Chabad’s concern over the use of the rebbe’s name also stems from the fact that scores of Chabad institutions worldwide bear some form of it, such as Schneerson Square, Cheder Menachem and Ochel Menachem Mendel, according to Lubavitch officials.

Though Cunin said Chabad attorneys are looking into the possibility of legal action, Pil said he doesn’t believe Chabad could win a lawsuit.

“You cannot copyright the name because you have at least 10,000 Schneersons,” Pil said.

The controversy highlights a growing schism and perhaps a final break between Pil and Chabad. It also reflects Pil’s public image problems since an April 23 article in the Wall Street Journal and earlier Bulletin stories scrutinized Pil’s Jewish Educational Center and car donation program that have brought in millions of dollars to his nonprofit organization in less than three years.

Pil said he believes “jealousy” of his success led to Chabad’s demands. But Cunin dismissed the notion.

“To be jealous of having one’s picture on the front page the Wall Street Journal — there are very few people who would be jealous of that,” Cunin said. “I don’t believe this is bringing honor to the rebbe’s name.”

Though Pil has never been an official Chabad emissary, he considers himself a dedicated follower of Chabad beliefs and of the late rebbe.

“I’m a Lubavitcher in my blood, in my philosophy,” he said.

Pil said that his family’s Lubavitch ties go back six generations and that his 7-year-old son is named Menachem Mendel, for the rebbe.

Pil has worked and prayed alongside several Bay Area Chabad emissaries over the past 13 years, including Rabbi Yosef Langer and Rabbi Ahron Hecht. In the past year, he has donated thousands of dollars to Chabad organizations locally and throughout the country.

But Cunin discounted Pil’s past efforts.

“People who give money don’t achieve any rights except to achieve God’s work,” he said.

To Langer, associating Schneerson with an organization receiving negative publicity dishonors the rebbe.

“That was the straw that broke the camel’s back — bringing the rebbe into it,” Langer said.

Nonetheless, the controversy doesn’t detract from Pil’s satisfaction about moving the school from its now-cramped, leased quarters in a two-story building next to Orthodox Congregation Chevra Thilim in the Richmond District.

During the next two weeks, the school is moving into a four-story building at 34th Avenue and Balboa Street. Renovations should be finished before school starts on Sept. 4.

Jewish Educational Center has signed a 10-month lease with an option to buy the $2,050,000 property, Pil said.

“It’s really exciting. I see there’s a very bright future ahead,” said Rabbi Yitzchok Tiechtel, the day school’s principal.

Until this month, the Jewish school’s new site was home to the junior and senior high of the Lycee Francais Laperouse, also known as the French school.

Lycee Francais decided to leave the 14-year-old building in order to consolidate its three locations into one larger campus in the upper Haight District, the French school’s principal, Ghislaine Hudson, said.

Meanwhile, Chevra Thilim is looking for new tenants, congregation president Charles Lewin said.

The Chassidic school’s move will allow it to add a sixth-grade class and to drop the age limit for preschool from 24 months to 18 months.

Last year, Tiechtel said, 80 to 90 children attended the school. He hopes the enrollment will only grow.

The new site is big enough to hold a library, kosher kitchen, computer room, social hall and gymnasium. The fenced roof will double as a playground.

“It will have everything a school needs to have. Until now, we physically didn’t have the space,” Tiechtel said.

In addition to educating children, the new school will offer adult classes and religious services.

Meanwhile, Jewish Educational Center is finalizing the purchase of a site at 11th Avenue and Clement Street in the Richmond District that will become a synagogue for Russian emigres. Despite earlier hopes, Pil said, he doesn’t expect the building will ready for High Holy Day services. Those will take place at the school instead.

Though Cunin hoped that Pil would simply change the school’s name after learning of Chabad’s position, the Chabad official said that at least the public will now know that no relationship exists between Chabad and Pil’s Jewish Educational Center.

But Pil said the mission of the two groups does overlap.

“We’re both trying to bring more Jews to Judaism,” he said.