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There is no different fluid listed for the Ecomatic compared to the other Golf Mk3 models in any literature I have.
According to owners manual revisions 1993, 1994Rev1(Ecomatic), 1994Rev2 (Ecomatic), and 1996, use specification: Hydraulic Oil G 002 000
According to parts catalogue: Hydraulic Oil G 004 000
listed for both engine-driven vane pump and electric pump.
My assumption is that G 004 000 was released after the Ecomatics were produced and superseded G 002 000 and was subsequently back-updated in the parts catalogue.
also enforces this suspicion as it is listed as being compatible with both G 002 000 and G 004 000
This is also the case with the factory coolant, when G12+ was released, the parts catalogue for earlier models was changed from G11 to G12+
Personally I would get this from the VW dealers to ensure it is indeed that either specification being adhered to, especially since this is an expensive part to replace.
It has crossed my mind a few times to change the fluid on my Ecomatics, not got round to it yet, but at least the fluid in it is clean