<<I had a 1971 250 with the 2.8 straight 6. The car had over 300K when I bought it. The previous owner had spent (gulp) over $7000 restoring it. Anyway, I put almost 100,000 miles on that car and it would only burn (leak) 1 quart in 3000 miles.>>
On the other hand, my '72 250 which I bought in '74 started to use oil at about 65K miles. Might have been valve seals but I never found out. The noisy CV joints at that mileage and 14 mpg were enough and I bailed out after driving it about 20K miles. But today, I followed a '72 220D for a mile or two in north Seattle. Aside from the noxious black cloud coming out the tailpipe, it looked like a pretty decent car. Under all the dirt I could see fairly shiny dark green metallic paint, an undamaged and straight bumper, brakelights that were not full of diesel schmutz, normal rear camber and a darkish tan interior. And a big for sale sign in the rear window with no price. Tempting. RLE