> Castrol Syntec 5W-40 has the VW 502.00 rating, but Castrol Syntec 5W-30
> does not have that rating.

As I understand it, Castrol Syntec 5W-40 is the only Syntec product that is
100% true synthetic. It's made in Germany, and is rarer than hen's teeth in
the US.

Amsoil 5W-40 is true synthetic, and Amsoil states that it meets VW 502.00,
but VW doesn't list it on its "approved" list.