I doesn't matter which method you use, drain plug or vacuum, the OM617 was designed to use vacuum as the preferred method of extraction, but they're both good ways, one way does not get more oil out more than the other.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.