About a month or so ago, I changed all the seals, VCG & valve stem seals (vacuum pump seals were also changed).
the car was smoking badly. The spark plugs were not fouled at all when I pulled them out. The car was using about 1qt oil/400 or 500 Km (250-300 miles).
Vacuum leaks exacerbates the oil burning issue, but curing them, don't fix it (N62), just alleviates the problem a bit.

After I did the whole work, the smoking issue stopped right away. And so far, I haven't added any additional oil either.
Another issue I had before, was: the oil level was fluctuating badly when trying to check it. It would show different readings on different days, after the car was sitting, and without moving it. This sounds bizarre, but it's the truth. For the last month, the oil level is consistent (a first for my car - I purchased it used, and with the problem)

If you haven't changed the original seals, as much as you don't want to do them, they're probably at fault. The myth goes they last max 60 k miles, after which they give up the ghost. They have a bad rubber, and a bad inside design, as opposed to the Elring Klinger ones. Don't wait until you start having also valve guides issues. My 0.02

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Stable: e92is, e46 M54B25, e83 N52, e53 N62 - sold, e39 M54B30 R.I.P.