Having just finished the job, I can see how those wrenches would help. Using the pipe + hex key, works and has one advantage - length can be varied a bit.

Only concern I would have with MB tool, is that it is a bit short and getting plugs out that have been in there for a while might not be that easy. I recall breaking a 3' piece of aluminum tube trying to release the plug on my 300D!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5