Is the car smoking blue or is the oil leeking out ?
if the is consuming oil by buring it while driving the faults are either :
Valve seats / Burnt valves
Piston Rings
or sump compression which can force oil into the combustion chamber causing it to burn it and expel the burnt oil via the exhaust system.
Either way, its going to pretty expensive on a 2002 5 series.
Burnt vales or worn valve seats will not make any new or strange noises.
Unless something major is broken or about to break the only sound an older engine or higher mileage motor will make it a tapping sound for a little while when starting, this indicates valve lifters and is not much to worry about, the reason it goes quiet later is because lubrication is not yet 100 % there yet (when a car is switched off all oil runs to the bottom.)
You oil consumption is quite low so it will not be enough to make the exhaust pour out blue smoke, but it always good to be aware of what color (you should not see anything if everything is OK) the exhaust gasses are.
Adding an additive that reduces oil consumption is an option, however I personally wouldn't advise it.
the additives change the properties of the oil, including viscosity and lubrication properties.
Your oil consumption is low, and a little oil that gets consumed by the engine will lubricate the top of the cylinder and valve seat etc. So its beneficial in a way. Your biggest risk is carboning up, however if you have it service regularly this won't be a problem.
what you can ask for, is next time you take the car for its service is to ask them to perform a compression test on all cylinders.
This may identify a problem related to your oil consumption.
So in the meantime just make sure your oil is always topped up and you have nothing major to worry about.
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Thank you for your diagnosis. I do not see any smoke and I do not see any indication of a leak so I assume one of your faults is the problem. Engine is quite, i.e. no valve tap noise..... does that indicate it's not related to valves? Is trying an additive that is designed to reduce oil consumption advisable? Thanks again. Walt
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