When mine was new it used a quart every 2500 miles, and increased to about a quart every 2000 at about 3 years/35K miles. Mercedes agreed to install the updated viton valve seals that went into production circa 1990, but I decided to wait until just before the end of the 50K warranty. Just before that the head gasket started seeping on the exhaust side, so they ended up rebuilding the head - all new guides, new exhaust valves, and, of course, the updated viton valve stem seals. Note that this is more than just a "valve job". It's a complete cylinder head rebuild.

When all was done it used a quart every 2000 miles. So your car has 200K miles and consumes a quart every 1800 miles. What's the big deal.

My previous '84 190E 2.3 only used a quart every 4-5000 in the 50K miles I owned it before buying the 2.6. The sixes are higher speed engines, and they consume more oil.

Use 20W-50, drive it, and add oil as required.

Duke