A class-action lawsuit claiming car owners are being misled about their vehicle's maintenance schedule is raising questions about how often Canadian drivers need to service their cars or even change the oil.

The trial for the class action wrapped up in Montreal on Sept. 20 and is now in the hands of a judge.

It began back in 2012, when the lawsuit's complainant, Thérèse Martel, went shopping for a new car with her partner, Michel Lacasse. Wanting a vehicle that was economical and wouldn't require frequent service, as they live far from an urban area, they ended up buying a Kia Rio from a dealership in Sherbrooke, Que.

Martel and Lacasse believed the regularly scheduled maintenance would come every 12,000 kilometres, as described in the manual's normal service schedule.

But when Lacasse brought the car in for its first service, he said he was told the oil had to be changed far more frequently and the 12,000-kilometre interval indicated owner's manual didn't apply to vehicles sold in Quebec because the harsh climate requires more intensive service.

Martel and Lacasse say they were ultimately told they had to follow the manual's alternate, severe usage maintenance schedule, which called for service every six months or 6,000 kilometres.

Martel is seeking $985 in damages — the amount she claims the couple paid in extra service costs in the two years they owned the car. If the class action is successful, it could apply to other Kia owners in Quebec.

Different climate, same policy

On the other side of the country, in Victoria, Nick La Riviere is asking similar questions about his 2018 Hyundai Ioniq, a plug-in hybrid.

Hyundai, which owns a controlling interest in Kia, also lists both a normal and severe service schedule in its manuals.

Two Hyundai engines are shown. Hyundai says the one on the left has been maintained properly and is clean. The one on the right has been neglected and is full of sludge. (Hyundai Canada)

La Riviere loves his car and says it's running great. A professional musician, he mainly uses it to drive to gigs around town.

Victoria is located in a temperate climate, where years have gone by without a day below zero and it rarely gets above 30 C in the summer. So La Riviere figured he would be able to follow the 12,000-kilometre schedule.

Yet when he called Hyundai Canada, he said a customer service representative told him Canadian owners have to follow the severe usage schedule in order to maintain their warranty.

"They told me I need to follow it because I might be driving in negative 40 or plus 40, which of course is crazy for Victoria, where we've got very mellow, gentle weather," he said.

In a statement to CBC News, Hyundai Canada said the customer service agent made a mistake.

"Broadly speaking, most Canadians fall under severe conditions simply due to weather and temperature," the company said. "Small pockets, such as Vancouver Island, experience milder weather and may be exempt. However, a vehicle on Vancouver Island could still qualify for the severe schedule based on how it is used."

In the same statement, Hyundai said it generally considers all of Canada to be a severe usage area when it comes to maintenance — but only in terms of weather, which it says is one of many considerations. Other considerations include regularly driving in heavy traffic or driving mainly on dirt or gravel roads.

"Across the automotive industry, harsh weather/temperature is one of the most important considerations for vehicle maintenance. Canada's weather is largely considered to be severe due to our harsh winters and vehicle maintenance should reflect that," it said.

Others moving away from severe usage schedules

George Iny, director of the Automobile Protection Association (APA), said he had not previously heard of an automaker designating all of Canada as a severe usage area.

"That's very strange because, of course, the primary [maintenance] schedule is the regular schedule. It would seem very odd that the [severe usage] schedule would become the primary schedule for the whole country," he said. "And in that case, why would you have a regular schedule in your owner's manual?"

George Iny, director of the Automobile Protection Association, says some manufacturers are moving away from severe usage maintenance schedules. (CBC)

According to Iny, some automakers are rethinking severe usage schedules altogether.

"Six thousand [kilometres] is probably the lowest that we've seen to date. And in some cases, the manufacturer has actually gotten rid of that interval — they don't have a severe usage schedule for severe usage," he said.

Most Canadians should probably follow a more frequent maintenance schedule — at least in the winter months, Iny said.

"For many of us in Canada, summer driving is not that hot and would match the less rigorous schedule," he said. "But winter driving — except Vancouver Island or in the southernmost parts of Ontario — probably is a severe usage situation because of the cold, because most of us live in a highly urbanized setting where we do a lot of short trips."

What about oil?

When it comes to oil changes in particular, however, guidelines are changing.

"It used to be a one-size-fits-all solution for oil changes. Everybody change their oil at 3,000 miles or 5,000 kilometres was pretty standard," said Kristen Huff, vice-president of Blackstone Laboratories, an oil analysis company in Fort Wayne, Ind.

"Engines are better now. And oil is better too," she said.

And as that chemistry and technology has improved, Huff says oil doesn't break down as much as it used to.

"So oil, in general, will hold up pretty well," she said. "And the only reason it ever really needs to be changed is that it's getting contaminated with metal or solids or contamination."

Hyundai and Kia both list a normal and severe service schedule in their manuals. (Ahn Young-joon, Lee Jin-man/The Associated Press)

Using a kit sent to them by the company, Blackstone customers can take samples of their engine oil and mail it back; for a $28 US charge, the company will analyze the oil and email the results to the owner.

"Think of it as sort of like a blood test, only for your car or your truck or any kind of engine," said Huff.

People are often surprised to learn how much longer they can go before needing to change their oil, she said.

"In my Subaru Outback, I run 10,000 miles (16,000 kilometres) easily. I could go 12,000 miles or 15,000 (19,000 to 24,000 kilometres)," Huff said. "My husband has a Nissan Frontier, same thing. He routinely goes 7,500 to 10,000 miles (12,000 to 16,000 kilometres) without a problem."

But at the same time, Huff says she has some sympathy for automakers when it comes to doling out maintenance advice to car owners.

"I feel for the manufacturers," she said, "because they can't print a manual for every situation out there and they have no control over where the car goes after it's sold."