What exactly is the difference between a 0W-20 and a 5W-20?

[996GT2]

Based on viscosity measures alone, it seems like a 5W-20 dino oil comes pretty close to the full synthetic 0W-20 oils. Is the difference in cold viscosity really that little between a 0W-20 and a 5W-20?

Mobil 1 Advanced Fuel Economy 0W-20 (Full Synethetic):

Viscosity, @ 100ºC, cSt (ASTM D445) 8.7
Viscosity, @ 40ºC, cSt (ASTM D445) 44.8

Pennzoil Platinum Plus 0W-20 (Full Synthetic):

Viscosity, cSt at 100°C 8.8
Viscosity, cSt at 40°C 46.3

Castrol Magnatec 0W-20 (Full Synthetic):

Viscosity @ 100C, cSt ASTM D455 8.6
Viscosity @ 40C, cSt ASTM D455 46.7

Mobil Super 5W-20 (Conventional):

Viscosity, cSt at 100°C 8.3
Viscosity, cSt at 40°C 46.9

 

[jlee]

40c is 104f, so not really cold:

 

[skyking]

Bingo!

 

[Fenixgoon]

needs moar cold for the 0W20 to be useful

 

[desy]

The synth will be better in the cold cold and longer change intervals
That's about it

 

[gorcorps]

about 5 Ws