At the TDI Club, someone asked about "cheap" 30-weight options -- cheaper than Elf Evolution 0w30 at $10-13/liter, that is. And in his case I believe it was for a 2002 TDI engine, so not requiring the VW505.01 or VW506.01 specification. I guess I made the mistake of suggesting German Castrol 0w30 or Amsoil HDD 5w30 -- and then remarking that I didn't know if the GC would be good for a normal 10k-mile OCI. And I got challenged on that, for suggesting that any VW505.00-rated oil might NOT be suitable for a 10k-mile OCI. I've been through much of the "GC & Euro/Import Oils" forum, and the diesel forums, and the VOA and UOA forums. And I can't find a definitive answer. It seems as though GC 0w30 is an outstanding oil for gasoline engines, at extended drain intervals. But, does it have the right stuff to run 10k miles or more in a TDI or other turbodiesel with EGR application? tdimaniac reported switching from M1 5w40 to the GC back in March, and mentioned a couple others (truman and fowvay) who were using it. Note that I am not considering GC in my own 2003 TDI -- I'm trying out the Elf Evolution, then will probably return to Mobil Delvac 1 unless the Elf results are truly outstanding. And IMO the Amsoil HDD 5w30 is a safe choice for TDI owners. But I would like more info so I can properly advise others.