75W80 oil vs 75W90 oil?

[DutchV40]

I always understood that the number before the 'W' states for the thickness of the oil when the oil is cold. So 75W80 is as thick as 75W90 except when warm?
When warm the only difference is that 75W90 is a little bit thicker?

[Ambiesda]

"I always understood that the number before the 'W' states for the thickness of the oil when the oil is cold. So 75W80 is as thick as 75W90 except when warm?
When warm the only difference is that 75W90 is a little bit thicker?"

SAE Viscosity Rating 75W-90
Relative Density @ 20º C 0.890
Viscosity @ 40º C, cSt 84.8
Viscosity @ 100º C, cSt 15.2
Viscosity Index 189
Flash Point (closed) º C 133
Pour Point º C -45


Viscosity Rating 75W/80W
Relative Density @ 20ºC 0.880
Viscosity @ 40ºC, cSt 56.3
Viscosity @ 100ºC, cSt 10.32
Viscosity Index 166
Flash Point,open ºC 159
Pour Point, ºC -39
API Service Level GL5

Hope that this helps

Regards

Malky

[DutchV40]

What does this mean in plain English?
75W90 much thicker at 40 degrees and a little bit thicker at 100 degrees?

[4 forty]

http://www.bobistheoilguy.com/visc.html

[DutchV40]

So if the figure of the viscosity is higher then the oil is thicker?

[4 forty]

Oils meeting the SAE's low temperature requirements have a "W" after the viscosity rating (example: 10W), and oils that meet the high ratings have no letter (example SAE 30). An oil is rated for viscosity by heating it to a specified temperature, and then allowing it to flow out of a specifically sized hole. Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating.