Originally Posted By: merconvvv
Originally Posted By: SonofJoe
Originally Posted By: userfriendly
"The system forces US oils to be far more volatile than they need to be".
Sonofjoe, is that a result of 0W & 5W winter grades attached to OEM approved engine oil for ambient -40C to 50C?
If so, chasing VI and one grade for all climate conditions is incorrect.
The main reason for this is the crazy way ILSAC has organised it's fuel economy tests. If memory serves, a US 5W30 has to have demonstrably better fuel economy than a 5W30 reference oil. Yes, you read it right. It says something must be better than itself!! No doubt this particular piece of madness was done in the name of 'simulating innovation'. The reality is that most US 5W30s have simply been formulated such that they are halfway to being 0W30s (by dropping the CCS, you drop the KV between 0 and 100°C which translates to a fuel economy credit).
For any base oil group, to drop the CCS, you need to lighten the base oil mix making the oil more volatile. If you lighten the base oil mix, you need to add more VII polymer, If you add more VII, you need to lighten the base oil mix a bit more. As often as not, if you add more VII, you need to add a bit more Ashless Dispersant to maintain piston cleanliness. Ashless kills your CCS so you need to lighten up the base oil mix again and the cycle keeps going round and round until you reach equilibrium, but what you always end up with is a oil that is far more volatile than it needs to be.
It's probably also worth mentioning that once you take that first misguided step to say a 5W30 must be better than a 5W30, the impact cascades to all of the other grades, both heavier and lighter.
Thanks for sharing your insight. Pennzoil sn rated sae 30 has pour point of -30c. How is that acheived for an sae 30 ? The viscosity index is close to 105 i think.
Base stock selection or PPD's would be my guess. Perhaps its blended with some GTL? The VI seems too low for any real slug of PAO, which would probably make it a 10w-30 like AMSOIL's and likely wouldn't be cost effective, making GTL more likely.