Teaching came naturally to Gary Madison. He knew how to communicate an idea or thought, so that others understood what he was saying.

But for Mr. Madison, his classroom was often under the hood of a Nissan or Infiniti automobile, and his students were co-workers, eager technicians, who wanted to know what he knew.

Mr. Madison knew Nissan-made automobiles so well, his family and some co-workers believe he was one of the longest-employed technicians in the country.

“He worked for the company when they still made Datsuns,” said Annabelle Madison, his wife of 45 years who lives in Woodstock. “He worked for them for 42 years, and there can’t be many who’ve worked for them that long or longer.”

According to co-workers and Mr. Madison’s employment records, he started working for Nissan as a Datsun mechanic in 1969. He became certified as a Master Tech while working at Nalley Infiniti-Marietta, where he worked for 22 years before he retired in January of this year. Mr. Madison’s tenure with the carmaker earned him the nickname Father Nissan, his wife said.

While he loved his job, his heart was in the things he did when he wasn’t under the hood of a car, his family said.

“He loved to fly,” said Keith Madison, a son who lives in Buford. “He probably wanted to work on a pilot’s license after he retired.”

But a couple of weeks before he retired, Mr. Madison was diagnosed with cancer. He’d had a number of aches and pains, before he went to the doctor, but after his diagnosis his health began to rapidly decline.

Gary Eugene Madison, of Woodstock, died April 1, days after suffering a massive stroke. He was 66. His body was cremated and a memorial service was held Wednesday at Sosebee Funeral Home, which was in charge of arrangements.

Mr. Madison’s vast knowledge of Nissan-made automobiles gave him an upper hand when looking for up-and-coming technicians who had natural diagnostic abilities. One of the techs he took under his wing was Donald Hamilton, who started at Nalley Infiniti-Marietta five years ago as an apprentice to Mr. Madison. From there, the two talked about more than cars, Mr. Hamilton said.

“I can’t tell you how much Gary Madison changed my life,” he said. “He helped me be a better man, not just a better technician.”

Mr. Hamilton said Mr. Madison was well-rounded, having extensive knowledge of not only cars, but several other subjects.

When Mr. Madison wasn’t at work, he was in his own garage, which he’d turned into a wood shop. He made wooden furniture and crafts for friends and family all of the time, his wife said.

“I’d take him to a store and show him what I wanted, and he’d make it,” Mrs. Madison said. “He was really good at it.”

His other love was amateur radio, his son said, and Mr. Madison made it a family affair.

“I think two of the happiest days of his life were when I passed my exams to get my license and when my daughter, his granddaughter, passed hers,” Keith Madison said of his father. “We’ve decided to keep dad’s call sign in the family.”

The plan is for Scott Madison, of Grayson, to obtain an amateur radio license so he can assume his father’s call sign, his brother said.

Gary Madison’s call sign, K4YBB, once belonged to a cousin, James Kelley. Mr. Madison had to petition the Federal Communications Commission to take it over when Mr. Kelley died, Keith Madison said. When it was time to pick call signs, Mr. Madison and his daughter chose to go with similar sequences.

“I’m K4YAA and she’s K4YCC,” Mr. Madison said. “Scott’s daughter is only 5, so she doesn’t know anything about this yet, but we’ll school her when she gets older. Dad would like that. He’d be thrilled.”

In addition to his wife, two sons and two granddaughters, Mr. Madison is also survived by his mother, Estelle Madison of Woodstock; and sister, Marsha Madison of Dahlonega.