I recently purchased a 2010 Mazda CX-7. At the time of purchase, it had done 95,000 kilometres. At 113,000 km, the turbo and engine failed because of oil-sludge buildup in the pipe between the engine and the turbo. We have been told by Mazda it is our fault as we did not get the car serviced within 10,000 km. Should the oil light not have notified us that there was an oil problem? - Norm
In most vehicles, the "oil light" will be first brought to the driver's attention when their vehicle travels around a corner.
The oil naturally sloshes to one side. If the oil level is low, the result will be an engine that is momentarily starved of its life blood. The oil pressure temporarily plunges and the oil warning light will flash, indicating to the driver to stop and check the vehicle's oil level.
Your Mazda's turbocharger has a shaft and turbine that rotate at speeds up to 300,000 rpm, requiring an uninterrupted flow of fresh oil. The feed pipe the dealer is referring to is the turbocharger's only source of that oil.
In your case, I believe the feed pipe became plugged by the sludge buildup, severely limiting oil flow. The turbocharger overheated, damaging the internal bushings, causing a catastrophic internal failure.
Turbochargers will often fail in the most dramatic of ways, with bits and pieces of metal being ingested into the engine. The oil light would not have come on in this scenario as the lack of oil was due to a restriction and not a low oil-level condition.
Lou Trottier is owner-operator of All About Imports in Mississauga.
Have a question about maintenance and repair? E-mail firstname.lastname@example.org, placing "Lou's Garage" in the subject area.