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I drive a 2004 Ford Mustang V-6 with 140,000 km on it. I have always used basic motor oil. I am curious what are the benefits to using blended or synthetic oil? Which is better for my car? I am confused with all these choices.

-Sandra in Burlington, Ont.

Your confusion is understandable. Motor oils are one of the issues most often raised in forums, discussions and Q&A sessions like this.

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Because of that widespread interest, there are number of viewpoints, sometimes conflicting ones. Mine is that you should use the oil recommended by the people who make your vehicle. They are the ones who designed, tested and developed the engine. They are the ones responsible for repairs under warranty should anything go wrong with the engine. They have a vested interest in ensuring that if an owner follows their recommended service procedures and intervals the engine will last for hundreds of thousands of kilometres.

While most manufacturers do not specify a specific brand of motor oil, they will all specify the grade and weight or viscosity of the lubricant. Having said that, those recommendations do not preclude the owner from using oil of a higher rating.

Oil is responsible for not only the lubrication and protection of moving parts, it acts as a coolant, absorbing heat that is partially removed as the oil passes through the filter, which is generally located where air passes as the vehicle goes down the road. Oil also plays a role in fuel mileage and exhaust emissions.

The standards or specifications are arrived at during engine development and testing. These standards are expressed in the code on a container of oil, ratings established by the American Petroleum Institute (API) including the grade and the viscosity rating. But there are a number of grades, some of which exceed the manufacturer requirements.

Generally speaking, higher standards are better; but in the vast majority of cases, they are unnecessary.

Standard motor oil is refined from crude oil, synthetic oils are synthesized from chemical compounds and blends are just that – a combination. There have been a lot of claims about the superiority of synthetics and blends, mostly by those who make and profit from them.

Synthetic oils are more resistant to breakdown at extreme high temperatures and may provide better lubrication upon startup at very low temperatures. Some manufacturers of high-end or high-performance automobiles use and recommend them. In cases where heavy towing is involved or other extreme conditions, synthetics may be preferable.

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But generally speaking I recommend the average consumer stick with the recommended oil and replace it according to the schedule in the manual – and don't forget to read those recommendations closely.

Don't skip over the "severe" service or similar section. Low mileage, frequent start and stops, short runs and dusty conditions can all severely shorten the life span of any oil – mineral, synthetic or blend. Save the extra cost of synthetics and use the savings to change often with a recommended oil from a recognized major company.

Fuel devices

What do you think of Fuel Doctor devices. Have you tried any, and do they work? -Jeff

The short answers are yes, I have tried some, and no, they don't work.

Years ago, I was sent an example of one that claimed to improve mileage by at least 15 per cent by "atomizing" the fuel, somehow "injecting" it with extra oxygen atoms etc. When I wrote my rather scathing review I was contacted by an outfit that claimed their device, which used simple magnets, achieved the same results – it didn't.

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Consumer Reports and the U.S. Environmental Protection Agency have tested hundreds of such devices over the years and have not found a single one with any redeeming benefits.

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