Oil Consumption - I am keeping OPEC happy

I have a BIG oil consumption problem on my 1981 300D of a scale that I have not seen. This car uses about a quart of oil every 200 miles. I am 99% sure that it is not burning as this level of consumption would be leaving a smoke screen everywhere I go. Also, I have I stood behind this car while it is running and there is no hint of oil burning. When I park the car I am not seeing oil dripping of any kind. The engine in general is dirty, but I have just not found a ‘smoking gun’. Perhaps I should first try to degrease the engine and see what develops. This is new territory for me as I have never owned a vehicle that ever lost more than 1/2 of a quart in 4,000 miles. Does anyone have any hints and history for this type of issue?