Worn internal engine components i.e. rings/valves allowing oil to get into combustion chamber at a greater rate than can be burned off by ignition in chamber
yes
Due to improper fuel-air mixtures.
A 1.9 TDI can hum at idle if the spark plugs foul. A clogged fuel filter can also cause this issue.
An engine that burns oil will usually foul the spark plugs. That, in turn will cause ignition misfire, higher emissions and likely damage the catalytic converter.
No spark from coil, bad plug wires, or bad plugs.
An engine that burns oil will usually foul the spark plugs. That, in turn will cause ignition misfire, higher emissions and likely damage the catalytic converter.
Gas mixed to rich
spark plugs tend to foul because too much oil builds up around the plug and it cannot work correctly. *sometimes* you can actually remove the plug, clean it, re-gap it, and replace it in the bike.
Spark plugs don't really burn out, they foul out. A spark plug is used to ignite the fuel/air mixture squirted into the cylinder by the fuel injector. The plug sends a spark and boom small explosion. However gasoline is not 100% clean, so it leaves carbon deposits on the plug. Over time these deposits foul the plug.
My best guess would be the plugs aren't igniting the fuel and it's collecting on the plug.
check spark plugs and wires
start with the spark plugs