Just had a similar problem in my '92 300E. My problem was noisy lifters. While they were fixing that they changed seals and small misc. stuff. Oil consumption is 0 now on a car with 219000 miles. I recommend if the noise is coming from the valve cover area that you take it to a good tech and have the lifters replaced. Don't want to go too long that way.
'92 300E Sportline (factory)
220000/ Black on Black