Different application, but for the citric acid flush of a cooling system, one of the first steps is to degrease the internals. Most of the recommendations I have read for this suggest the use of Shout stain remover from the grocery story. Soaps are discouraged because they will foam forever (hyperbole!). Perhaps Shout is something to consider.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).