My friend has a 2002 TDI Jetta which he loves, except for engine oil changes. The dealer insists that the engine requires a special synthetic oil that only THEY can provide because of some special ingredient. He's led to believe by the dealer that use of any other synthetic engine oil will damage the engine and void his warranty. Yesterday he showed me the dealer's "brand new version" of this special synthetic engine oil and while the label included all the latest API "S" and "C" (I believe it was CL) ratings, it also included mention of a "505" classification for VW. At almost $7/quart, he's investigating his options. Since I am considering the purchase of a TDI before the 2007 emissions guidelines hit, this issue of special VW TDI engine oil concerns me as well. Does anyone in the TDR community know the specifics regarding this new "special" synthetic engine oil for the VW TDI? Can a high-quality synthetic with a CL rating safely be substituted without damaging the engine or aggravating the folks at Volkswagon?