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My wife and I recently traded in our 2007 Nissan Versa for a 2012 Mazda3 Sport GS-Sky. We take pretty good care of our vehicles and I get an oil change about every 6,000 km. However, we average only 12,000 km per year, and that means only two oil changes a year. At signing, the sales manager at Mazda dutifully informed us that if we failed to follow Mazda-recommended maintenance intervals, which requires an oil change every four months or 8,000 km (whatever comes first), we would be putting our warranty in jeopardy. Is there truth to this or was he just trying to drive more business to the dealers' maintenance department? – Todd in Ottawa

It's surprising how many motorists emerge from the gas station after paying for a fill-up with an armload of "necessities" – a tabloid, a scratch-and-win, a chocolate bar and a bag of chips – yet they balk at shelling out for service crucial to ensuring the longevity of their vehicle.

I'm not suggesting that you're buying candy bars instead of changing your oil, but I would recommend to all new vehicle owners that while you might save a few bucks by skimping on regular service, you'll save much more if it comes time for warranty repairs by presenting the dealer with a vehicle that's been well-maintained. If you want to take advantage of the factory warranty, you must play ball with the manufacturer.

It may be difficult to accept that a car sales manager was telling you the truth, but here's the official line from Mazda Canada:

"Proper vehicle maintenance protects you from major repairs resulting from neglect or inadequate maintenance, and keeps your vehicle running efficiently, reliably and safely. The Mazda dealer was correct in advising that a 2012 Mazda3 Sport GS-Sky requires maintenance every 8,000 km or every four months, whichever occurs first. This recommended maintenance schedule was developed expressly for Canadian driving conditions and takes into consideration varied driving habits. Mazda Canada strongly encourages Mazda owners to follow the recommend maintenance schedule or you could void your vehicle's warranty."

There is little doubt that an oil change is one of the most important things you can do for your vehicle. At 12,000 km annually, you're coming in well below what Statistics Canada tells us the average motorist clocks in a year (just over 16,000 km). In your case, three oil changes does seem a touch excessive. Or does it? It's always a good idea to ask questions and seek a second opinion.

"As long as it's a gas engine, I advise people to do an oil change every 5,000 km. But if a car's sitting in the garage for six months of the year, there is no need for an oil change. When people question that, I say, 'If you bought a quart of oil and sat it on the garage shelf for six months, would you throw it out?' No. Same goes for your engine, if it's sitting in the garage it's not working and therefore not getting dirty," says veteran mechanic Russ Perry.

"If you say to a dealer, 'I often take the bus and only put 4,000 km annually on my car' and they still tell you to do three oil changes a year, then you know they're crazy. But how you justify that for a warranty is another matter, they may still say you need three even though you're not putting mileage on," says Perry.

Even the experts seem to differ in their opinions of how often oil should be changed. Car makers base their figures on averages and so there's surely a significant margin for error dependent on conditions, type of driving, etc. To combat this, some manufacturers offer an oil-life monitoring system that advises, via a dash-display, the percentage of life left in the oil and when it requires changing.

After checking with General Motors of Canada officials, they said the average interval between oil changes for vehicles equipped with their oil-life monitor is roughly 12,000 km. They add, however, that this is "dependent upon load, temperature, and number of combustion events [engine RPM]"

According to GM, rather than depend on fixed oil change schedules that may not be suitable for all situations, the monitoring system customizes the oil change schedule based on the vehicle's engine and transmission type, and the individual's driving habits.

A Mazda sales associate I contacted said the following about the likelihood that warranty work would be approved or denied on the basis of the frequency of oil changes:

"The bottom line is, if you brought your vehicle in for an engine-related warranty issue, and they took the engine apart and found the oil had atrophied because it had been in there too long, and it was dirty and thick, and this was a contributing factor as to why the engine failed, that would void the warranty. But if you're in to do something under warranty and the oil is perfectly good, no one will quiz you about when you changed your oil.

"I've been doing this for 20 years and I can count on one hand the number of customers who've had warranty work denied due to lack of service. You have to completely ignore your car for two or three years before things will get so bad that voiding the warranty will be an issue. Even doing an oil change only once a year will not void the warranty.

"It's only ever going to be an issue for those people who think their car will deny the laws of physics and go 30,000 or 40,000 kilometres without an oil change. People who change their oil in their driveway, or at Jiffy Lube, or come to us on a regular basis, are going to be perfectly fine from a warranty standpoint."

Discuss your driving habits with your dealer service centre, and see what they have to say. If you want the peace of mind of the warranty, you're best to follow what the dealer advises so you don't encounter any unwanted repercussions down the road. Once your car is off-warranty, you can let common sense prevail and care for your car as you wish.

E-Mail your automotive questions to Ask Joanne at

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