Mr McCarroll said he had no plans to quit work anytime soon.
"I've been sacked a couple of times over the years. I told them 'You didn't hire me so you can't sack me' and I ignored them," he said yesterday.
"A lot of people have said 'You should leave', but I think that if you enjoy the work and your health is up to it, why not stay?"
Bob's parents, Reg and Betty McCarroll, were dairy farmers at Mareretu, 13km north-west of Maungaturoto, but young Bob wasn't interested in farming. He left that to his younger brother, much preferring to commute to the Central Garage daily on a 250cc BSA motorcycle.
Roads were unsealed in those days. Reg McCarroll drove a 1936 Chevrolet and there were plenty of Model A Fords - and even one or two Model Ts still in service.
Harvey Cullen, 71, son of Central Garage founder Ron Cullen, joined Bob in mechanic's overalls in 1957. Together with Harvey's older brother, Ken, they replaced rings and valves in old Fordsons and tackled other major tractor overhauls in farm paddocks.
Tractor repairs still fill a big part of Mr McCarroll's work day, together with his role driving the garage tow-truck. He also drove an ambulance for more than 20 years and he fills in as a school bus driver.
He doesn't own a car, still preferring motorcycles. He owns a Honda Gold Wing 1500 and enjoys long runs with Harvey Cullen, now a dairy farmer with a Kawasaki Nomad 1500.
Mr McCarroll married in 1968, but separated 15 years later. He has a 41-year-old son, Brandon, who lives in Perth and his 39-year-old daughter Tania Toka is the mother of his two cherished grandchildren.
For a 76-year-old, Mr McCarroll's health is good. When he had a medical examination to pass his driving licence a few months back he was told he was blind, but he paid $1000 for glasses and passed with flying colours.
He's had to give up bowls because he's so busy with job-related duties. And he's hopeful he will be be able to keep working for many years.
"There's too many going too early," he said, describing how he he had recently come across a name he knew in a newspaper deaths column. "I thought he had died ages ago, and then I realised it was the son of the bloke I knew and he was only 55."