Noack Question

[FrankN4]

Looking at Brand X oil, I see they have a line of synthetic blend oils in 5W-20, 5W-30, 10W-30, 10W-40, 15W-40 and 20W-50 in one of their lines. If I look at the NOACK for each oil, in order, it is 13, 13.5, 10, 13, 9, and 8.

Can I infer anything about the base oils from the Noack? It appears the 5W-20, 5W-30, and 10W-40 are very similar. It also appears the 10W-30, 15W-40, and 20W-50 are more related to each other, and better. Dare I think that maybe the 10W-30, 15W-40, and 20W-50 might have more synthetic blended into the base oil?

 

[JAG]

The largest factor there (in that brand) is probably the viscosity of the base oil mixture, while the types of base oils used in each grade is secondary. When more VIIs are used, the viscosity of the base oil mixture must be reduced, thereby raising volatility. And for a given amount of VIIs, as the viscosity increases, the volatility decreases.

 

[FrankN4]

Jag

Does that mean that a higher viscosity base oil naturally has a better Noack, ALL ELSE BEING EQUAL?

Does it appear that in my example, they have used 3 different base oils, or only 2?

 

[JAG]

Originally Posted By: FrankN4
Does that mean that a higher viscosity base oil naturally has a better Noack, ALL ELSE BEING EQUAL?

Definitely.

Originally Posted By: FrankN4
Does it appear that in my example, they have used 3 different base oils, or only 2?

I can't say. There are too many unknowns. What brand is this anyhow? I'm just curious...knowing that still will not allow me to answer to this question.

 

[FrankN4]

This is Valvoline Durablend synthetic blend. The add pack appears to be identical across the line. The biggest variable was the Noack.

 

[JAG]

I see, that makes sense. Those volatilities are somewhat high for the respective viscosity grades, so I figured it wasn't a full synthetic.

It has been said by reputable sources that 5W-20 non-full-synthetic oils often use a higher proportion of higher end base oils than same-brand 5W-30 and 10W-30. That's needed largely to keep the volatility within acceptable limits. Your data above shows the 5W-20 is actually slightly less volatile than the 5W-30, so that 5W-20 probably uses more expensive base oils than the 5W-30.