The Car Talk search feature is a bit iffy at best.
Can Ethanol contribute to sludging? I would say yes because many factors contribute to that problem and gasoline quality is one of them. Others are the environment, engine state of tune and condition, oil type, driving habits, environmental conditions, whether the crankcase ventilation system is working properly, and so on.
I would not start fretting over a turbocharger unit just yet. In a shop setting and when an oil consumption complaint exists the first step is always, always, always, run a compression test (both dry and wet) and possibly a leakdown test as a means of checking piston ring condition.
Since there’s often misinterpretation, or even total lack of knowledge of, what compression readings are supposed to be (even by some shops) what you should be looking for is:
Compression readings of around 185ish on all cylinders.
Any low cylinders (say 165 give or take) should be retested with the wet method. If the readings jump up (say to 185) then there’s a piston ring problem.
Stuck piston rings can be caused by oil sludging, overheating, etc.
Oil consumption can also be caused by faulty valve seals. Overheating can ruin valve seals and there is no test at all for those as they’re a replace and pray item.