Whitish smoke

[BMW GL]

Good day all.
I am new to this forum. Please bear with me if I am posting this question on the wrong forum.
My 1996/12 E39 540i (Vin last 7 digits: BW71172) just started smoking. Big white billows on pull away and little while driving. It was suggested that either the ccv valve is shot or if it is a coolant smoke, the head gasket. This was about two weeks ago.
The car is mostly driven on weekends for short distances.
Car stood for 6 days. No coolant loss. No oil loss. Started yesterday with no smoke from exhaust. Idling changes when either dipstick or oil filler cap removed. No oil in water and visa versa. Only detected slight fuel smell from exhaust. Did see little greyish smoke with bonnet open from rear of engine and oil burning smell. (Could be rocker cover gaskets leaking?) I checked the suction on the dipstick tube and oil filler cap. A lot of suction on both.
Now totally confused. Should it not be smoking constantly if either the ccv valve is shot or head gasket blown?
:skit:

 

[Sankekur]

White smoke could also be brake fluid that leaks from the master cylinder into the vacuum booster that gets sucked into the engine.

Suction at the filler cap and dipstick doesn't indicate that the PCV valve is working correctly as a faulty PCV will result in too much vacuum in the crankcase hence oil getting drawn into the intake. The PCV valve is relatively inexpensive and easy to replace so it might be a good place to start either way.

It might also be valve stem seals.

Have you done a compression test?