Check it out the way you would any other MB diesel.....
Start it cold and check for smoke.

Running B99 will clean out a ton of gunk, and if it has a 2 tank
well just think of it as extra range.

If it is a good running car, no need to run away.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project