Anyone know how the scale works? You see the red label inside the jacket with, for example, Nitro Fuel or Road Fuel, plus the number 1-4. Which is the warmest - 1 or 4? What do the words mean? what conditions are they suitable for? So many questions....!

Check out this page from o.com:

http://oakley.com/apparel_chart/nitro_fuel/

It has a chart comparing nitro fuel, road fuel, etc.

Here you go:
http://oakley.com/apparel_chart/rocket_fuel/

As ever, quick, accurate and useful!
Thanks guys!