Skip to main content

The Globe and Mail

Is my garage taking me to the cleaners?

My local automotive workshop is enthusiastically recommending TerraClean treatment to clear carbon deposits from engine parts and also the exhaust system. Is this a good thing? Why do manufacturers not include this as a recommended service? – Louis

The reason manufacturers don't recommend such service is that they do not see it as necessary.

With today's cleaner, lead-free fuels, there is little carbon buildup that cannot be handled with regular use of quality top tier gasoline.

Story continues below advertisement

There may be some carbon deposits in an engine, but far less than was the case years ago, when dirty fuels caused big problems.

Today's electronically-controlled ignition and injection systems, combined with the cleaner fuels, assures more complete combustion. What deposits do remain are usually burned or cleaned off depending on the quality of fuels used and the type of driving.

The biggest contributions come from infrequent driving and short trips that do not let the engine get up to full operating temperatures so the deposits can be burned off and harmful chemicals evaporate. Older engines, or those in a poor state of tune, could also have a problem with carbon deposits if oil is being allowed into the combustion chamber past poor valve seals or past the piston rings.

There are a host of aftermarket products that make all sorts of radical claims to cure everything from carbon deposits to arthritis. Your shop makes a healthy profit from this product, which probably does no harm, plus the labour charges involved. If your vehicle is healthy and shows no signs of excessive oil consumption, this treatment is unnecessary.

Use quality fuel, change oil and other fluids as recommended and your engine will last hundreds of thousands of kilometres without assistance from such products.

Low-mileage vehicle

We recently bought a 2005 Nissan XTrail from a local dealership, who told us they received it as a trade-in. The somewhat remarkable thing about the vehicle is the mileage, which was just less than 15,000 km. We had the British Columbia Automobile Association (BCAA) do a full inspection, and its mechanic said it checks out as consistent with that mileage, and we ran a vehicle history report that shows it has been insured locally through the life of the vehicle. We're confident that the mileage is accurate, but I wonder if there's anything we should be aware of that could be problematic in a vehicle that has been driven so little over the past eight years? – Don

Story continues below advertisement

If the service was performed as recommended during those eight years, you've found yourself a gem.

There are plenty of us out there who own vehicles that are driven very little – I've got a pair that each see less than 1,000 km a year.

There are two reasons for older, low-mileage vehicles: 1) They have been stored for an extensive period of time, or 2) they are used regularly, but sparingly.

Vehicles that have been stored can become problematic if that storage was not done properly. Otherwise, tires, seals, gaskets and numerous other materials dry up or lose effectiveness. If proper care was taken to address these issues, there should be no problem.

The vehicle that sees use occasionally is actually a better bet if that use included driving it long enough to reach full operating temperature, allowing moisture and other condensates to be burned off and all critical bits and pieces to be exercised and lubricated.

One item you should look at, though, if they are still original, are the tires. Regardless of appearance or mileage, tires have a lifespan of five to seven years before they lose their effectiveness.

Story continues below advertisement

Send your automotive maintenance and repair questions to

Report an error Licensing Options

The Globe invites you to share your views. Please stay on topic and be respectful to everyone. For more information on our commenting policies and how our community-based moderation works, please read our Community Guidelines and our Terms and Conditions.

We’ve made some technical updates to our commenting software. If you are experiencing any issues posting comments, simply log out and log back in.

Discussion loading… ✨

Combined Shape Created with Sketch.

Globe Newsletters

Get a summary of news of the day

Combined Shape Created with Sketch.

Thank you!

You are now subscribed to the newsletter at

You can unsubscribe from this newsletter or Globe promotions at any time by clicking the link at the bottom of the newsletter, or by emailing us at