You don't need the citric flush...
you need to flush again with the degreasing agent. That part number can be found earlier in this post. Citric flush is used to remove scale and build up, you need to clean out the oil.
Degrease first, then follow with the citric flush.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.