Can 5W-30 flow at temperature X exactly like 0W-20 at temperature Y?

[Javed]

X = 30° f
Y = 10° f

Can the difference be that big, like 15 degrees?

In this graph it looks like roughly 5 degrees. The warmer it gets the less the difference.

 

[Jetronic]

I believe the graph uses degrees celsius. so 5 °C works out to 9°F

 

[SubieRubyRoo]

Yes.

 

[ka9mnx]

That is called Viscosity Index and is widely variable depending on the base oils used and Viscosity Index Improver additive.

 

[Glenda W.]

Yes. Especially in a Jeep with oil temps between 200f to 250f (off roading).

 

[Hohn]

Because every oil has a finite viscosity index, there is always some temperature difference that can make two oils have the same viscosity.

 

[Pablo]

Define flow.

 

[Cujet]

Yes, that's how all of this works. To make matters even more complicated, there are synthetic 15W and 20W-XX oils that pump more easily at -50ºF than some 5W-30 oils.

Even among 'high tech' oils, there are some lower viscosity AN based oils that won't pour or pump below about -30ºF and some PAO based higher viscosity oils that will pour at -44ºF or even lower.