I had an 05 passat tdi that was specced for 505.01. I believe that the 229.51 would be fine in the 505.01 spec cars. 505 is an older spec than the 229.51 and it was created to protect the fragile camshafts in the tdi. Many did well using mobil turbo diesel truck in the tdi. I too, plan to use some Mobil one TDT in my om642 now that I have no dpf.
2007 limited crd 2wd, 3.07 ratio, GDE eco tune, dpf delete, tnadanzig resonator delete