I replaced the valve stem seals last night on my 1982 240D and my oh my what a tremendous difference. The valve adjustment smoothed out the cold startup and idle. The stem seals stopped the plume of smoke at every take off from a stop. I let it sit and idle for 5 minutes last night and then showered down on the accelerator to see if she would blow a thick cloud of blue smoke and there was NO SMOKE AT ALL! I am now expecting to see that quart between changes reduce to a negligible amount now. I love this car!!!