You've been using a very thick oil w50 for a long time.
I'm afraid it might have done some damage, so if you choose the right oil I.e 0w20 or 5w30, the SYMPTOMS of that damage might become apparent. Like, little oil reduction.
A super thick oil like w50 might mask the symptoms n keep on wearing down the engine.
5w40 is still quite thick, but at least better than w50.
you may switch to it or go directly to the right oil 5w30. Your choice.