I just sold my 1993 300 sd for this reason. At 210,00 miles Iwas putting two quarts of oil in every 250-300 miles.

I changed turbo and the turbo shop said "It did not look that bad it is purfect now"

I lost the glow plugs so I took the head of see how I had the intake maniford off--I know crazy ratinal. The machine shop said The head looked real good you would never know it had that many miles I don't think oil was getting by.

My compression was 400 in every cylinder no cylinder off by more than 10 points.

Someone told me it was a warped piston and it would pull yhe oil in onhe bottom of the stroke.