"Should be" Viscosity Values with Blackstone UOAs

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While reviewing several recent UOAs, I noticed some variance in the "Should Be" values for viscosity parameters and thought I'd question Blackstone about this. Below is the exchange, what are your thoughts?
Originally Posted by Initial Question
I have a question regarding the "Values Should Be" for Viscosity. On this most recent sample, the oil in question is a 0w-30 which lists ranges of 58-65 @ 210*F and 9.6-11.9 @ 100*C. However, on other samples for this same weight some of the ranges you've provided as "should be" ranges are 57-67 and 9.4-12.4. I've also seen 53-59 and 8.2-10.2. Again I am seeing this for 0w-30 oils being used in other 2.0T Giulia. Why are there variances to what these ranges are? Shouldn't the should be values be consistent with SAE viscosity guidelines?
Originally Posted by Blackstone
That's a good question. The viscosity ranges tend to be brand specific, and we'll tailor the "should be" values to what the oil's data sheet calls for.
Originally Posted by Follow Up
Thank you for the response, Joe. Is there a reason Blackstone presents the information this way? Using Xw-30 as an example, SAE states that the viscosity (cSt) must be between 9.3 and 12.5 at 100*C. As I previously mentioned, some UOAs I have seen show a range of 8.2-10.2 being given. While 10.2 is certainly within spec, 8.2, according to the SAE would be considered an Xw-20. It seems to me that it would not only be easier on Blackstone's end to utilize the SAE parameters, but would also deliver a more accurate analysis with regards to the industry standards.
Originally Posted by Blackstone
If every brand stuck to a strict SAE guideline, then it would be easier to just have a set range for every oil, but that's just not the case. And as such, we'll put up the viscosity range stipulated on the oil's data sheet as the "should be" range.
 
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Quote
And as such, we'll put up the viscosity range stipulated on the oil's data sheet as the "should be" range.
Except that an oil's data sheet shows a specific viscosity value, not a range.
 

RamFan

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Originally Posted by Quattro Pete
Except that an oil's data sheet shows a specific viscosity value, not a range.
Bingo! That's kind of my point in this. It seems as though Blackstone is arbitrarily (to a certain degree) assigning a viscosity range based on a specific value listed on the PDS. Frankly I don't care what the viscosity is with respect to its starting viscosity, I care that it stayed within grade based on SAE ranges. I understand that there is benefit to comparing it to the starting value, but ultimately that's not my (nor most people's) concern. To add to this, I didn't give them a product name for my sample. I simply stated Synthetic 0w-30, so what PDS was used to find this range?
 
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This "should be" range that Blackstone gives has been discussed here a few times before. Here is one, but I know there have been others, I just can't easily find them: https://www.bobistheoilguy.com/foru...sity-blackstone-labs-results#Post4423477 What I believe they're doing is actually looking at their UOA database history to establish a range that they've seen from other samples for that grade/oil type, but I don't know their exactly methodology. Plus, like in your case, since you haven't given them a product name, then what are they actually comparing it to in order to provide that "should be" range? EDIT: Here is another thread, alas, not a whole lot of activity in it: https://www.bobistheoilguy.com/foru...ackstone-viscosity-vs-sae-j300-viscosity
 
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Yeah, that "should be" range is almost worthless, even with the criteria they claim they are using from the spec sheet. For instance, I sent them in a sample of BC 0w-30 and the viscosity was slightly over 12 which is in near perfect harmony with the Castrol spec sheet. Instead, I got the "out of reference" from them on the basis that the viscosity shouldn't be higher than 11.9. So unless one knows better, you might think that there as something wrong with oil but the answer is that Blackstone isn't really tracking their own database correctly or perhaps better stated, it's just lumping all 30w oils together which isn't correct. My samples always say the brand and in this case, the sample paperwork said it was BC 0w-30 A3/B4. i don't know how much more info I can communicate to a company who is in the oil testing business.
 

dnewton3

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The problem for all the main choices (Polaris, Wix, Blackstone, etc) is that they do OIL analysis, not STATISTICAL analysis. While they are good at one thing, they are not really trained in true statistical methodologies, at least not that I can tell. To be fair, they are not claiming such abilities, so we cannot hold them accountable for things they don't profess to be selling or claim to be good at. There's nothing wrong with Blackstone stating the "should be" vis range, as long as you understand what it does and does not represent. You asked them; they answered. It's that simple. You may find it to be misleading, because you believe it should be strictly based on the SAE ranges. This is a topic for each consumer to decide for themselves. It's not really any different than their "universal averages". An average is close to worthless, without knowing the "range" of variation (standard deviation). But that does not stop nearly all BITOG members from using the service and comparing their data to the UAs. Hence, I wrote the normalcy article. And what of the "limits" from other services like Polaris? They hold that info proprietary; what makes their "limits" the end-all/be-all perfect number???? UOAs are tools. You have to understand their benefits and limitations, and the conditions around their uses, to really glean the most from them. That the OP contacted Blackstone and asked, and got his answers, is about a good as you can expect it to be.
 
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