Actually Amsoil is also a Group 4 oil as stated in an email I received from one of their Lubrication Specialists;
"Group IV -Chemical Reactions: Group IV base oils are chemically engineered synthetic base stocks.
Polyalphaolefins (PAO's) are a common example of a synthetic base stock. Synthetics, when combined with additives, offer excellent performance over a wide range of lubricating properties. They have very stable chemical compositions and highly uniform molecular chains. Group IV base oils are becoming more common in synthetic and synthetic-blend products for automotive and industrial applications (hh)."
"AMSOIL uses only Group IV PAO's"
Not quite sure you reasoning on this one.
"Genuine" Nissan oil that is used for car servicing at Nissan Dealerships is a 5W30.
I don't see too many Nissan's driving around blowing out oil.
My mate had his NM35 Stagea serviced at a Nissan dealership (inc oil change) and he certainly is not "Blowing oil out"... and yes, he loves boost
Oh yeah, currently I am using Motul 300v Chrono (and have been for the last 46,000kms) but will probably be changing to the 300v Power Racing (5W30) next service.
I change every 10,000km's, and have been using either K&N or Amsoil oil filters.
Runs quite nicely!