I called Castrol yesterday, and found out where to buy Castrol Syntec 5w-40 directly from Castrol distributors in my area. The only downside is the closest distributor is still over 100 miles away. I can find the 5w-40 (part# ZVW352540S) at the VW dealerships pretty easy, but it is $6.72 (ouch) a bottle -- this should be the Belgium product. The 505.01 spec 5w-40 (part# G052167A2) is even more at $7.67 which is different than Belgium product I believe.
The next time I take a trip north I might swing by the Fernandina Beach distributor, so until then I'll just have to wait.
For anyone that is interested, you may contact any of these Castrol Distributors for Castrol SYNTEC SAE 5w-40.