Quote:
2012 Audi A7 3.0T. Recently they sent out a notice about a warranty extension because of excessive carbon buildup on various parts of the engine.
Which parts? Anything needs to actually hit that carbon, and you need to know the location of the problem.
Does anything actually help? Or is manual cleaning the only way to correct it until they invent better parts or whatever will actually cure the cause of the problem?
I understand the letter to say, "Audi has determined that, under certain driving conditions, carbon buildup can occur in the engine cylinder head secondary air ports.
...
In our continuing efforts to assure proper performance of Audi vehicles, your dealer will diagnose and, if necessary, clean the engine cylinder head secondary air ports to remove the carbon buildup at no cost to you as long as the vehicle remains within the time and mileage limits of this warranty extension.
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This warranty extension covers only the diagnosis and cleaning of the engine cylinder head secondary air ports to remove carbon buildup. And should you ever sell the vehicle, this warranty extension is fully transferable to subsequent owners."
If the technician has to remove parts and physically clean them, forget about spending any money on snake oil to add to your gas. Or spend all you want. It won't make any difference to the engine.