It had been mentioned in this forum that M1's 0w40 was different in Europe to the 0w40 in the US. I was bored and decided to take a look at the PDS from Mobil 1's USA site and European site.
After looking at the various product data sheets, it appears that the following formulations have the EXACT same properties:
Mobil 1 0w40 European Formula (USA)
Mobil 1 0w40 Protection Formula (EU)
Mobil 1 0w40 Turbodiesl (EU)
Mobil 1 0w40 New Life (EU)
So it appears that, much like German Castrol, 0w40 is a true european oil that is not diluted for the US market.
After looking at the various product data sheets, it appears that the following formulations have the EXACT same properties:
Mobil 1 0w40 European Formula (USA)
Mobil 1 0w40 Protection Formula (EU)
Mobil 1 0w40 Turbodiesl (EU)
Mobil 1 0w40 New Life (EU)
So it appears that, much like German Castrol, 0w40 is a true european oil that is not diluted for the US market.