I've got a "89 190e with about 82,000 mi. that I bought about a year ago. It too consumes a lot of oil...about 1 qt. every 700 miles or so. I've noticed that oil use is very variable...sometimes I'll go a long time with little use and other times it seems to drop quicker. I also suspect the valve seals or guides, but have not yet had it worked on. I don't see any smoke, and compression is good. No major leaks are evident. I just keep dumping more oil in it.