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We just moved into a new house and it has a heated garage. I like the idea of keeping it heated all winter to give my cars a bit of a break from the cold every day. The question is: how hot? I've always heard that heated garages are bad for cars, but is that just sour grapes from guys who wish they had garage furnaces?

– Oscar, Mississauga

If your garage is too warm and your car's coming in covered in ice, snow, and road salt – that daily dose of heat could potentially turn your car into a hot mess, experts say.

"When you're moving your car in and out of a heated garage, that build up of snow and ice is constantly melting and then refreezing," says Patrick Brown-Harrison, instructor at SAIT Polytechnic in Calgary.

In a heated winter garage, your car is wet more often than it would be in a unheated garage – and water causes rust, especially when combined with corrosive road salt.

"You can get accelerated corrosion on the undercarriage and body panels of a vehicle," Brown-Harrison says.

Regularly washing and drying your car can help keep off the accumulated salt and ice, Brown-Harrison says.

A heated garage can be more humid than an unheated garage – and when humidity mixes with road salt, it starts to eat away at the metal on your vehicle. Constant shifting between hot and cold, by bringing your car in and then taking it out again, can also deteriorate seals on your car.

"They're constantly becoming hard and soft as the temperature changes," he says.

If you are going to heat the garage, Brown-Harrison recommends not keeping it too warm.

"For day to day use, keeping the garage around 8C will control the melting and the effects of high moisture on the surfaces of an automobile," Brown-Harrison says.

Heating the garage solely to give your cars a nightly break from the cold could do more harm than good – and will cost you a bunch of money.

An unheated garage can keep a car from the worst of the cold and elements, especially if it's well-insulated.

But there are other reasons to heat a garage, say if you're using it for a workshop. Or, if you're storing a car for the winter.

"Storing a car for the winter indoors is ideal, and if it's heated, fine – it will keep fluids from freezing," says Stephen LeRoux, professor at Centennial College in Toronto. "But most home garages aren't heated. This doesn't make them unsuitable to store a vehicle."

Send your automotive maintenance and repair questions to Jason Tchir at globedrive@globeandmail.com