1992 300D, intake manifold is all oily and valves are all crudy, oil is low also, is the seal on the turbo going?

Could be. Check the crankcase vent hose that goes to the turbo inlet. Hopefully blowby is not a major source of oil consumption.

Sixto
87 300D

It is normal. Oil from the crankcase vent is what coats the intake, that oil combines with the soot from the EGR to form the crud on the valves and low oil is the driver not checking the oil level and topping it up like they should be.

i understand all that, but you dont add oil everyday, adding oil is not a thing that you should have to do daily, checking yes, but the oil is going somewhere you gotta find out yes. i was just seeing if anybody has seen or has replaced a turbo on these cars at all? or how long they last

As long as you take care of them (turbos)

There are "cartridges" available to replace your turbo's inners...If, God forbid,
you lose one due to low oil in the sump.

"Based on the condition of your engine and the service (or lack thereof),you
may be checking + adding Lubricants multiple times Daily".

You are the "Captain" of the Vessel.

My opinion is that the turbo seals gradually wear with age and allow seepage into the intake. Eventually it gets to be a problem.........one quart every 1K miles and the owner addresses it.

The '86 has been consuming a quart every 1500 miles or so since I purchased it. It's definitely turbo seals as the engine has minimal blowby. One of these days I'll pull the turbo and rebuild it. But, the oil consumption is not killing me..........