Meaning that it has detergent/dispersant properties more suitable than 300V for street use. Probably mix of base stock to limit oxidation etc. But, it has high HTHS which you obviously want, but also that HTHS limits which approvals can pass (it is questionable whether it could pass MB229.5 or BMW LL01). Why bothering getting MB229.3 since it is outdated (Mobil1 does that though). It is Ester based, so highly doubt oxidation is suitable for LL01. So why bothering with approvals? They developed oil for people who want dual use, but maximum protection at track. At that point warranty is irrelevant. It is targeted for customers that are more knowledgeable about oils than regular drivers.So what does that mean?
Meaning that it has detergent/dispersant properties more suitable than 300V for street use. Probably mix of base stock to limit oxidation etc. But, it has high HTHS which you obviously want, but also that HTHS limits which approvals can pass (it is questionable whether it could pass MB229.5 or BMW LL01). Why bothering getting MB229.3 since it is outdated (Mobil1 does that though). It is Ester based, so highly doubt oxidation is suitable for LL01. So why bothering with approvals? They developed oil for people who want dual use, but maximum protection at track. At that point warranty is irrelevant. It is targeted for customers that are more knowledgeable about oils than regular drivers.
I am actually strongly considering this oil for my BMW since it will see track.
That's easy, the awesome is in the fixation and not in these oils. The reason for your choice of the 5W-40 grade simply remains unclear when you're primarily after negative Noack and maximum HTHS. HTHS is nothing but another viscosity figure (representing some behaviour under medium shear rates and temperatures). Will cost some fuel and rob some power. Same with Noack, if the figure is four, six or eight won't make for an impressive oil. Let your Subaru add some fuel to it and the figure is a new one anyway as it's only a weight loss from some lighter fraction leaving a big narrative ,-)
I got this from the NASIOC forum (quoted below) and most subaru forums recommend looking for high HTHS and low noack for turbo subaru's....unless I'm doing it wrong then I'm all open for suggestions what should I be looking for instead, I'm not very technical or knowledgeable but I'm trying to learn..and I'm not a specific brand fanboy I don't care what brand the oil I'm using is as long as it's very good....
''High Temperature-High Shear Viscosity (HT/HS)
HT/HS is a measure of dynamic viscosity, it represents the oil’s thickness within the vital hydrodynamic bearings of an engine. It is the most important measure of how well the oil will perform as a hydrodynamic lubricant. HT/HS is measured at 150°C (302°F) which is a worst-case temperature for most engines. The higher the HT/HS, the stronger the hydrodynamic film in the engine’s bearings. Thus, the correct HT/HS is more important than the KV100 (SAE Grade) when selecting oil. If the oil formulator publishes their HT/HS it's best to ignore the grade and KV100 and base your choice on the HT/HS. As we will see later, different industry specs categorizing motor oil are based in large part on HT/HS and those specifications will tell us much about the oil's HT/HS even if the formulator doesn't publish a specific value.''
An ordinary HDEO 10W-30 with HTHS 3.6 ends up thicker at really high shear rates than the 5W-40 with its HTHS of 4 (which is not exactly what people tend to make of such a difference in HTHS).
The Sport Ester 5W-40 looks better than the 5W-50 version with HTHS of 4.5 in the end would. For the same reasons. So it's clear that HTHS remains a figure for 150°C and one million / second only. The straighter 10W-30 ends up even better and that's not told by this NASIOC with its worst case statements. (Of course lower_HTHS_is_better also doesn't apply.)
On the other hand there'd be no sports in these bottles at all if these contained oils that by some magic remained chewy at 20 millions per second. Bad enough what they're costing and wasting in milder areas as they are, but they'd become thinnies on the track under high shear. That's the sports in them.
First of all you need to face the fact that HTHS is in no way any insurance against "shear". Not against permanent viscosity loss from shear and not against temporary viscosity loss from shear. Higher gain in HTHS viscosity from polymeric boost in fact means higher temporary viscosity loss at high shear rates. "Shear stable" would only mean good resilience of the VI enhancers themselves so they'd have a longer life but still not be of any help at high shear rates. ->shear thinning
It's not "better", there's no general "better" at all until you try to focus on a few aspects. The best all around would probably be one with higher "natural VI", better FM et al. if you want best protection when you floor it. For areas in the engine seeing high shear rates some kinematic viscosity @100°C in the oil pan is quite irrelevant and HTHS-V still only means a hint. In your table for those three you'd principally want to see the combination of the ROWE's HTHS and the Ravenol's KV100, preferably from "naturally high VI" = not much VI boost.
So, above table basically shows no difference at all and while these oils in fact form a kind of group among all 5W-40s you basically have to believe in them as this group until you make other oils actually look worse in some regard.
shows an exemplary compact table that deals with the articulation of viscosity curves for higher shear rates.
I shall try to fit your oils in Gokhan's worksheet which can be a bit of help looking at it.
Or are you trying to tell me that as long as the oil meets the minimum HTHS and noack there is no point comparing those characteristics, and I should be looking at something else to determine the best oil for my application? Subaru turbo boxer engines are notorious for shearing oil even under normal driving conditions....that's why i'm looking at HTHS and noack...
The first lines in this now are from Gokhan's table – I hope I left them unmodified...
Then I brought in the 10W-30 HDEO I had in mind and finally your group of three (with the values from your table).
The column called BO DV150 (base oil's dynamic viscosity) is meant to illustrate something like the oil's viscosity @150°C and high shear rates (as opposed to the medium shear rate in HTHS). This way a different picture is drawn and HTHS can get relativised quite a bit. It's no tool to establish rankings, but HTHS & Noack don't lead to a ranking either. Just an additional perspective.
Our group of three can't be expected to have a foundation from base oils particularly good in natural VI and the "calculator" seems to support the presumption that they'd suffer quite some viscosity loss.
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I have now fully automated my A_Harman index, effective VII content, and base-oil viscosity calculator by building in the ASTM D341 viscosity - temperature relation (Walther formula) into the spreadsheet. If you want to calculate these values for an oil, you can either (a) make a copy of the...www.bobistheoilguy.com