5. Car service center

Express Oil Change & Service Center

Service: oil change and other auto service

Founded: 1979

Number of franchises: more than 170

Headquarters: Birmingham, Ala.

Investment costs: $300,000 to $1.5 million

Fit for 50-plus? Your staff oversees the cars; you oversee the business.

But: Investment costs are high.

Spotlight: Bill Ross, 64, Birmingham

Ross bought his first Express Oil Change franchise in 2000 as an existing business; he was able to keep his day job as a CFO for a manufacturing company. "I was looking for something to invest in, mostly for retirement," says Ross, who left his CFO position in March 2010.

He now has two centers and a third opening in April. He plans on sticking with the business for a while — "as long as my health holds out. Maybe another 10 years."

Ross now puts in 20 hours a week, much of it from his homes in Pensacola, Fla., and Birmingham.

His advice: Be patient. Most franchises are "not an overnight success, and you have to put some money into the operations."

Geoff Williams writes about business and personal finance. He lives in Loveland, Ohio.