Originally Posted By: OVERKILL
Originally Posted By: bobbydavro
That table being quoted talks about group I and the chart on PAO vs group 3 ignores effect of ppd.
The 2nd chart in the image shows the effects of mileage on two different PPD's in an oil with a relatively narrow spread: 15w-40.
Question for you though: Given that we know VII's break down/shear and PPD's degrade or change with age, this would generally lead to the assumption that if you are using a lube with a primarily PAO base, that since you don't have to use PPD's, that low temp performance is going to be more consistent, and if the base oil blend has a relatively naturally high VI, less VII's as well. Other than the expense (and assuming the additive package we are using already deals with seal compatibility) I don't see a disadvantage
So is cost the primary driver in all of this? (I think it is a safe bet to assume it is) And if yes, then are oils with high percentages of PAO (like M1 EP 0w-20) a "better deal" due to the cost of their formulation? At first glance, it certainly looks that way.
Obviously this is being intentionally over-simplified for the sake of the discussion but the topic of base oil selection for a finished product being safe to ignore due to the performance of the end product has been something of a newer thing on here; Trying to get people away from focusing on an oil having PAO or Esters and ignoring everything else and focusing more on the approvals and performance specs of the fully formulated lubricant.
Along with that we saw some of our favourite products evolve in various ways. GC's departure from being green, then from being German. M1 0w-40's cold temp performance taking a hit, PAO being swapped out for VISOM, then the SN formulation brought greater shear stability with it and the most recent change appears to be a switch back to PAO with a 50-60% PAO content.
There's no denying the performance of the end product being the most important thing. But I know for those of us that acknowledge that there is still a secret obsession with base oil composition, and that's what this discussion is about.
And some tangents from that would be:
1. Cold temp performance - AFE 0w-20, using the index discussed, has very little VII in it. We know it has a fair slug of PAO in it, so is its cold temp performance going to remain more consistent through your typical Canadian winter than its Group III-based counterparts like TGMO?
2. If #1 is true, then would EP 0w-20 be even better in that respect? Their indexes are extremely close, despite the fact that we know that the latter has almost 2x the PAO in it.
3. Chasing VI (in the manner in which has been depicted on here, you may have missed that party Bobby) far beyond the natural level of the base oil blend seems to be a game of chasing a characteristic that almost guarantees lower shear stability and greater performance degradation with age. Shannow gave a few examples of that earlier in the thread.
Comparing M1 AFE 0w-20 and TGMO for example, the one's MRV is a natural function of its base stocks, the other is a function of its PPD's, as we know it has zero PAO in it. The Index being discussed supports that. So despite the fact that the AFE product has a much lower VI (172 vs 2xx), it would seem, based on the current discussion, that it is going to be the more "stable" product. And its cold temperature performance that much more reliable.
Well though out overkill.
K so it's not that I am disagreeing here however I don't recall seeing any used oil analysis with TGMO that sheared in any significant way.
So what does that mean exactly?
I recall Caterham saying the VII used in tgmo were cutting edge and didn't break down as VII typically do but I think my question is why prop up a lesser base oil with more stuff that doesn't either lubricate or help the tribo chemical film in order to achieve a finished product that performs no better than a simpler formula?
I guess I'm asking why complicate things by adding this super duper viscosity index improver and use an arguably lesser basestock just to achieve equal performance to an oil I can just grab of the shelf that doesn't have all this special stuff in it.
Did that even make sense
