When firefighter Douglas Oelschlager was leaving St. James for duty in Manhattan, he turned to his wife, Suzanne, with a grin and said, "Isn't it great how I love to go to work?"

On the morning of Sept. 11, Oelschlager had finished his night detail with Ladder Co. 6 on Canal Street in Chinatown and reached his day detail at Ladder Co.15 on South Street in time to climb aboard a rig heading for the World Trade Center. Suzanne Oelschlager learned that her husband probably reached the

30th floor of the North Tower, guiding civilians to safety. Ladder 6 firefighters eventually returned safely. The South Street firehouse reported 14 missing.

Oelschlager, 36, was born on a Naval base in Maine, where his father was stationed. His father, a Navy man, also died at age 36. And his grandfather was 36 when he was reported missing in the South Pacific during World War II.

Although only 16 months with the New York Fire Department, Oelschlager, a captain in the St.James Eagle Hook and Ladder Co., was a Long Island volunteer fireman for almost two decades.

"It was a calling with him. I called him 'Joe Fireman.' He was always helping people," his wife said. "He died the way he lived his life."

At his St. James firehouse tomorrow night firefighters will hold a memorial service beside a black bunting-draped fire truck. "It was his pride and joy," his wife said.

"Doug helped design the fire truck two years ago," said John Gleason, a fellow firefighter in St. James and in the city. "He went to the factory to inspect it being built. That's the kind of fireman he was. He paid attention to every detail, made sure all the equipment on the truck was right. He was a seasoned firefighter." Both men were assigned to Ladder Co. 7 in Battalion 8 on East 29th Street, although Oelschlager was rotated to other ladder companies.

Before being called to the fire department in 1999, Oelschlager worked in building engineering at Park Towers in Manhattan. He was especially valuable to the fire department because "he knew high-risers inside and out," his wife said.

He was also a family man. "When his daughter's Girl Scout troop was threatened to be dissolved for lack of a co-leader, Doug volunteered," his wife said. "We had a 50-50 marriage," she said, with Oelschlager deeply involved in raising their daughters, Brittany, 11, and Kayla, 8.

Kayla said she wants to be a firefighter "and be a hero like Daddy."

Oelschlager grew up in Santa Barbara, Calif., where his mother, Teri, and brother, Daryl, still live. Moving to Long Island, he graduated from Syosset High School in 1983 and enlisted in the Seabees. He also volunteered with the Oyster Bay Fire Department.