from a 2007 posting here...
PART ONE:
For engines that are NOT "pumpe-duse" or "common-rail". This is for the older-design mechanical rotary distributor pump engines. ie, ALH
You must use a synthetic engine oil, recommended viscosity 5w40 although 0w40 is also permissible (and in the case that the oil meets specifically one of the VW 505.xx standards then the viscosity does not matter, it could be different), AND in the fine print on the bottle that lists what standards that the oil conforms to,
it must list either VW 505.00, ACEA B3, ACEA B4, API CK-4, CJ-4, CI-4, CH-4, or CG-4.
(Note: "Either" means ANY ONE OF, not necessarily all of them. For example, if it's VW 505.00 but doesn't list the others, that's fine, because VW 505.00 is "one" of the standards listed and you only need "one".) But do NOT assume that any synthetic oil will meet these standards. READ THE BOTTLE. For example, most versions of Mobil 1 do NOT meet these standards (they are meant for gasoline engines).
Also, any oil that is suitable for a PD [below] is fine for a distributor-pump engine too [ALH]
Many "European car" synthetic oils meet these requirements. So does Mobil Delvac 1 5w40, Shell Rotella Synthetic 5w40 or 0w40 [aka T6], PetroCanada Duron Synthetic 5w40 (can be special ordered at any PetroCanada OilChangers location in Canada), Castrol Syntec 5w40 European-car formulation, and quite a few others. IF IN DOUBT, READ THE LABEL.
The VW part number for the oil most commonly used at the dealers is ZVW-352-540S = Castrol Syntec 5W-40 (VW 505.00 rated, suitable for non-PD TDI engines; not suitable for PD TDI engines). If they use the PD oil (see below) that's OK.
do not use anything that is not FULL SYNTHETIC, turbo heat requires FULL SYNTHETIC.
VW Part num: ZVW-352-540S "Castrol Syntec 5W-40"
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PART TWO:
for PD engines --- it must state VW 505.01, NOTHING ELSE!!! 5W-40 again
can be found, but you may need to look hard [in 2007]. That .01 makes a big diff!!
it must be certified by VW, "Meets or Exceeds" on the label is NOT GOOD ENOUGH!!
beware Amsoil, they won't pay for certification so it only says "meets or exceeds".
Out of warranty and it's up to you of course...
VW Part Num: G-052-167-A2 "Castrol TXT 505.01"
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PART THREE:
for Common Rail --- it must state VW 507.00, NOTHING ELSE!! 5w-40 or 0w-40
a very "new" oil [in 2007], hard to find, may have to go to VW dealer directly.
VW Part Num: GVW-052-195-M2 no major lable equiv yet [as of 2007; in 2021 there are several].
And I Will Add: 507.00 is NOT a suitable substitute for 505.01 that .01 is VERY SPECIAL, the PD needs
extra cam lobe protections.
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So, 14 years ago they were saying 0W is "ok".
FWIW I'll stick with Walmart's Shell T6 5W-40 for my ALH, about $20.