Metroplex,
There are 0w-20 synthetics being sold in Europe for use in turbocharged engines. One example is the "Fuchs" Titan synthetic, which is an ester based product. As a practical matter the high temp/high shear viscosities of the 0w-20/5w-20 oils are very close to some of the 0w-30 and 5w-30 oils, so the difference is more perception than reality.
For example:
XL-7500, 5w-20 - HT/HS is 2.9 Cp
Mobil 1, 0w-30 - HT/HS is 3.0 Cp
Synergyn 0w-20 - HT/HS is 2.8 Cp
If these engines work with the Mobil 1, 0w-30 or 5w-30 you could also use some of these 0w-20 and 5w-20 synthetics with no problem. I'd expect oil temps to be slightly lower with the xw-20 grades due to a reduction in "intrafluid" friction. As a result, oil pressure with the three oils shown above will be almost identical. I've been running the Synergyn 0w-20 in a 2.4L Tacoma pickup for the past six months and it works very well. About 2% better fuel efficiency than the Amsoil 10w-30 synthetic and NO oil consumption.
TS