I would only use Mann filters or OE from the dealer. Other brands have a nasty habit of collapsing which causes all sorts of shifting problems.

The torque spec on the pan bolts is REALLY low, like 7 Nm. Overtighten, and you may warp the pan which will then leak.

I've always re-filled with Mobil 1 synthetic ATF, and I highly recommend it. When I bought my '87 300TD, it had about 270k miles, and shifting was very inconsistent. After about 10k miles with the M1 and new filter, all was much much better. I know others who have had the same results with the Febi fluid, so perhaps simply fresh fluid and filter (and driving time) is all that is really required.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC