I misstated earlier. My apologies.
Apparently, Mobil is trying to steer buyers to a particular viscosity based on the type of vehicle that the oil will be used for, and is labeling the viscosities as follows:
10W-30: Higher-Mileage Vehicle Formula
5W-30: Newer Vehicle Formula
0W-30: Enhanced Fuel Economy Formula
0W-40: European Car Formula
15W-50: Performance Driving Formula
If you know what viscosity you want - and, for the NSX, I stick with Honda's 10W30 recommendation - just buy based on the viscosity on the bottle, and don't worry about what catch phrase they use with that viscosity.
Here's the wording on Mobil's website (thanks for the link above):
The Right Grade For You
While every grade of Mobil 1 with SuperSyn™ provides exceptional performance, each viscosity is geared toward a specific application. If you've been successfully using a particular viscosity grade, you should stick with it. But if you find that selecting the right viscosity is sometimes confusing, you can follow these guidelines.*
*Use these as guidelines only. You should always follow the viscosity grade and API service category recommendations listed in your vehicle owner's manual.
[This message has been edited by nsxtasy (edited 20 May 2002).]