Here's a riddle to consider.

When is it a good thing for a hybrid car to burn more gasoline?

The answer, at least according to Ford Canada, is when the hybrid in question is driven in a cold climate, but only for short distances.

CHECK OUT: 2013 Ford Fusion Hybrid: Quick Winter Gas Mileage Test (Mar 2013)

After a customer complained of problems with her Fusion Hybrid mid-size sedan, Ford told her to drive in a way that makes more use of the gasoline engine, reports CBC News.

Lisa Sweeney bought her Fusion Hybrid in May 2014, and after about a year of driving, she began experiencing issues with it.

A check-engine light triggered multiple visits to the dealerships, making the car unavailable for about three months total.

2013 Ford Fusion Hybrid, test drive, Catskill Mountains, NY, Mar 2013

2013 Ford Fusion Hybrid, test drive, Catskill Mountains, NY, Mar 2013

The problem turned out to be thick, milky sludge building up in the Fusion's oil cap.

"We believe sludge occurred in this customer’s vehicle because the engine in the vehicle did not run to full operating temperature sufficiently to burn off moisture that naturally occurs in a running vehicle," Ford Canada said.

The company added that this is exacerbated by cold temperatures.

ALSO SEE: Four of 10 Ford Fusion mid-size sedans sold in LA are hybrids

Ford noted that Sweeney only averages around 3,000 miles per year—compared to the 12,000 miles covered by an average owner annually—in an area of Canada "with more extreme winter climate."

The carmaker recommended that Sweeney make routine 15-minute drives at highway speeds, and conduct more frequent oil changes.

But Sweeney was dissatisfied with that solution.

2013 Ford Fusion Hybrid, test drive, Catskill Mountains, NY, Mar 2013

2013 Ford Fusion Hybrid, test drive, Catskill Mountains, NY, Mar 2013

Nothing in the Fusion Hybrid owners manual indicates that such drives should be necessary, she told CBC News.

Regular drives solely to use gasoline also defeat the purpose of a hybrid, she said.

MORE: Suit says '13-mile' range for Toyota Prius Plug-In Hybrid was deceptive

Sweeney purchased a five-year extended warranty with her car, but is concerned Ford will no longer honor it if she keeps having sludge problems.

She now wants Ford Canada to buy the car back, and has said she will not buy a another Fordor hybridagain.

[hat tip: Brian Henderson]

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