can viscosity at 40c or density be correlated with an oils W rating?

[apollo18]

hey all! ive been looking around and i noticed that for example
castrol edge 5w30 has a slightly higher density but a lower kv40 vs something like mobil 1 0w30 afe which has a slightly lower density but a slighty higher kv40

i normally would have assumed that m1 afe 0w30 would have a lower kv40 but its higher then the castrol egde 5w30

so do any of these values correlate with an oil being a 0w vs a 5w? or is it just how it performs during the 0w vs 5w test ?

thx

 

[Jetronic]

Density relates mostly the base oil composition. PAO, which has very good cold flow properties is lighter in density than mineral oil. It's likely the Mobil 1 product contains more PAO than the Castrol.

 

[weasley]

Additives are also generally significantly denser than base oils.

Remember also that kinematic viscosity is absolute viscosity/density.

 

[BMWTurboDzl]

so do any of these values correlate with an oil being a 0w vs a 5w? or is it just how it performs during the 0w vs 5w test ?

thx

No. The cold temp tests are conducted at temperatures well below 40C. Minus 5C to minus 40C

 

[kschachn]

You didn’t get a good answer in this other thread of yours?

Is 5W and 0W essentially the same flow/lubricity at 40-60F +?

Hello correct me if I am wrong however this is the info that I learned over the years and not sure if I am correct or not The first digit before the W is the winter rating So 0w will flow better then 5w at super cold cold temperatures However for this example lets use we are comparing a full...

bobistheoilguy.com

 

[Rand]

You didn’t get a good answer in this other thread of yours?

I was going to link that post then realized he was the OP in that thread too so not likely he missed it.