W124 Oil consumption

[nick126]

I have an 89 420sel that is going through about 2qts of oil every 500 miles or so...have tried heavier 20w50 to see if it would help slow down burning but it's not...have no visible oil leaks but do see smoke especially on heavy acceleration. Any ideas? Car starts, idles, and runs well otherwise. 135k on odometer. W126, not 124.