spark plugs fouled with oil. blue smoke from tail pipe.
You can tell this before an oil change. If you see blue smoke coming out the exhaust your engine is burning oil. If you're oil level is low and you have no oil leak your burning oil.
The engine is burning oil
your car has oil burning in the combustion chamber of your engine , need to rectify the engine block and replace piston rings
The engine is burning oil.
An oil leak is always going to be out of the engine as the engine contains oil and the car does not. I think you are saying you are loosing oil with no apparent leak. If that is the case the engine is burning oil and that is why you see no leaks.
oily deposit on the spark plugs electrodes
Oil on engine burning as engine overheats. Sort of common sense, don't ya think?
engine is burning oil could be valve seals or piston rings
Oil burning is usually connected to engine wear. Valve seals and piston rings wear out and allow oil to pass into the cylinder during combustion.
engine burning oil
The engine's dipstick will indicate the correct or incorrect level of oil within the engine .
Engine sludge is what the dealer told me Engine sludge is what the dealer told me