I have a bottle of PAG 46 oil. Is it compatible with the compressor on a 2006 VW W12 Touareg?
Yes, it should be compatible.
According to this Denso parts catalog, compressor DCP32052 is compatible with the VW Touareg W12.
This compressor needs 200 cc of Denso ND-8 oil, which is equivalent to PAG 46.
As a side, the same compressor is used on the following models:
- VR6 Touareg 3.2 L (manufactured between 05/2002 and 02/2005)
- W12 Phaeton 6.0 L (manufactured between 04/2002 and 05/2005)
- VR6 Phaeton 3.2 L (manufactured between 04/2004 and 05/2007)
- W8 Passat 4.0 L (manufactured between 09/2001 and 05/2005)
It depends. I could tell you that i've read of shops servicing every vehicle with PAG 100 (ISO VG 100 is apparently an universal viscosity grade for most if not all compressors) and never having any comeback at all. Even more, some shops seem to use POE ISO VG 100 even when PAG oils are required, and nothing happens.
The biggest problem with oil viscosity is that using too thick of an oil might prevent proper oil return to the compressor especially with reduced evaporator load (low amb temperatures for example). That said, i've seen my car's compressor, whose label calls for a PAG 46 oil, serviced and ran with a PAG 125 oil on another car make with no problems, so it might also depend upon compressor design.
But reading the label on the compressor in your vehicle, and looking for any indication about the compressor brand, model, oil quantity and type, and trying to follow it as much as you can, is always the best course of action.
Especially when some VAG group (Audi, Seat, Volkswagen, Skoda) cars are known to come with 4 different compressor brands for the same car (Denso, Valeo, Delphi, Sanden).
Anyway, one thing is sure: modern Denso swash plate compressors require ND-8 oil (which is a PAG ISO VG 46 double end capped oil, that is, each molecule, a chain in that case since it's a polymer, is "closed" by two inert groups at each ends, so that these ends and therefore each molecule can't react with water, so that the molecule would be more stable in general and most importantly humidity won't be a problem when you're refilling the compressor with oil).
PAG 46 is however used in any modern variable displacement swash plate compressor, be it Denso or not.
Denso rotaries (scrolls and through vanes), on the other hand, require a PAG ISO VG 100 oil.