A '99 model calls for G12. G12 (G12 G012A8D) and its successor G12 Plus (G012A8FA4) have been discontinued and superseded by G12 Plus PLus (G012A8GM1). These three G12 variants, which are available also from Pentosin, are compatible with each other and may be used. Switching to G05 is another option, but after 10 years a switch may not be ideal.
Here's a rundown on Volkswagen/Audi coolant specification norms. Please note that nowhere on the DEX-Cool page does it mention ANY of these standards. G-12 is not a standard, it's a product name.
Norm TL 774-C = Volkswagen's old blue/green coolant (G11). Not used.
Norm TL 774-D = Good old G12
Norm TL 774-F = Good old G12+
Norm TL 774-G = latest and greatest G12++
When Havoline wants to state that their coolant meets VW's TL 774-G standard then I'll believe it's the same. Until then, I'll continue to note that coolant manufacturers make differing formulas for Volkswagen and for General Motors.
And while VW is in business to make money, one thing that they don't make is anti-freeze. They simply sell the stuff along with a zillion other retailers.
Dan, I don't know what is available in your neck of the woods but a very common producer of VW coolant is a company named Kost.
Kost USA, Inc. produces a coolant called "DefendAL Heavy Duty Extended Life Coolant/Antifreeze (DEFEND AL HD ELC AF). This specific product is sold to many outlets such as European car service centers not associated to the manufacturers. This product does specifically carry the VW TL-774D standard along with a dozen other manufacturers specs. Their web site is Kostusa dot com.
Of interest is the fact that the VW specification meets all of GM's Dexcool standards (1825, 1899M, 6277M) but the Dexcool does NOT meet VW's TL-774 standard.
This has been debated on this website before but a interesting fact is that Ashland Chemical (Zerex) produces all of the North American coolants for the European car companies here in North America under license from BASF of Europe (the OEM supplier). The coolant that you buy at BMW, Mini, VW, Audi, Mercedes, Smart, etc, and labeled as OEM coolant is in fact manufactured by Ashland Chemical.
I guess the real question is whether DexCool would cause any problems in a VW car. I don't know whether it would or not. If I were going to try it I would specify that the Zerex product be used as opposed to the Havoline product. One thing that is a absolute certainty is that the OEM coolant in the VW/Audi cars is a definite step above anything else I have ever experienced in my life. It's one of the few products that is worth every penny that it costs.