I use Chevron Delo 400 Synthetic 5W40 in my TDI. I live in the Houston area, Conroe, and here is my source:
Whitener Enterprises, Inc.
PO Box 400
Cleveland, TX 77327
281-592-5891
I bought a case of gallons-six to the case for $74.49 or $12.415/gallon. They were very nice...