HTHS numbers

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quote:
Originally posted by Patman: This is what Mobil 1 emailed me just now about the HTHS numbers: >SAE 0W-20 (soon to be available): >2.6 >SAE 0W-30: >2.9 >SAE 0W-40: >2.9 >SAE 5W-30: >2.9 >SAE 10W-30: >2.9 >SAE 15W-50: >3.7 Not too impressive. Although I recall someone here posting higher numbers before. Perhaps their specs are too vague. Saying it's greater than 2.9 could mean it's 3.5 in reality. Although at the same time, why would they quote a lower number? Wierd.
Mobil continues to perplex me with they way the answer (or don't answer) tech questions. To say that 0w40 has an HT/HS of >2.9 is ridiculous since the oil carries an A3 rating, which means it has to have an HT/HS of >3.5.
 

Patman

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Good point G-man! I sent them a response asking them about that. Hopefully they'll respond here before the end of the day since I can't check my work email address from home.
 

Patman

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I'm also trying to find out the HTHS for Royal Purple. I emailed PRRPILL (who sells RP oil and posts here occasionally) but he hasn't responded yet.
 

Patman

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Does anyone know the Royal Purple HTHS numbers? What about any other HTHS numbers for popular oils? Neo? Synergen?
 
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Curious where that 0w40 M1 HTHS data came from? The only thing I have seen is 3.6 or 3.55 on their global PDS. And everyone keeps saying 0w40 is their global oil, same everywhere. THis is why I don't believe any data Mobil reps give out.
 

Patman

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Originally posted by novadude: Forgive my ignorance: What is HTHS? [Confused]
High Temperature High Shear. A higher number is better.
 

MolaKule

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HTHS is the number related to the shearing of an oil at high termperatures. Oil thins out at high temps, as we already know. This test determines how much the oil shears back due to mechanical shear stresses at elevated temps; the elevated temps being caused by the shear pressures themselves.
 
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quote:
Originally posted by MolaKule: HTHS is the number related to the shearing of an oil at high termperatures. Oil thins out at high temps, as we already know. This test determines how much the oil shears back due to mechanical shear stresses at elevated temps; the elevated temps being caused by the shear pressures themselves.
Is that the same thing as the degree with which the oil behaves thixotropically?
 
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Some interesting numbers. The Castrol GTX has better numbers than the Syntec in 5W-30 form. Also, Citgo 5W-30 has higher HTHS than Citgo 10W-30. Any thoughts on that?
 

Patman

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quote:
Originally posted by Green Max: Some interesting numbers. The Castrol GTX has better numbers than the Syntec in 5W-30 form. Also, Citgo 5W-30 has higher HTHS than Citgo 10W-30. Any thoughts on that?
A lot of it has to do with the viscosity of the oil. Castrol GTX 5w30 is thicker than Syntec 5w30 at operating temperature.
 

Patman

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I just got another email from Mobil 1 customer service, clarifying the HTHS numbers to more typical numbers as to what they see:
quote:
SAE 0W-20 (soon to be available): >2.6 (typical N/A yet) SAE 0W-30: >2.9 (typical 3.0) SAE 0W-40: >2.9 (typical 3.6) SAE 5W-30: >2.9 (typical 3.2) SAE 10W-30: >2.9 (typical 3.2) SAE 15W-50: >3.7 (typical 5.1)
 

Patman

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quote:
Originally posted by Steve S: On the subject does a 20/50 then protect better than a 10/30 in the proper climate of course.
This is a debate which will rage on in here forever, but here is my take on it. There aren't many cars out there that need a thick 50wt oil, and many of them will see higher engine wear numbers too, due to this thicker oil not being able to flow as well. The majority of our really incredible UOAs on here are with thinner 5w30 and 10w30 oils. I've only seen one 50wt analysis which looked really awesome (it was 10w50 Castrol)
 
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A 50 weight will always protect better than a 30 weight by shear virtue of a thicker hydrodynamic barrier. Now, whether it's necessary and/or we are willing to pay a fuel economy penalty for it is another story. HT/HS numbers are probably important because they give an indication of how well an oil stands up under punishment..but, it's only 1 test. I believe the UOA's don't give the whole story. Traditionally, thicker oils have been used and are recommended when 1. racing (high temp/high punishment conditions) 2. long drain intervals (I can't see too many engines going 10k mi. intervals on convenience-store 5-30) 3. engine life is a priority (Euro. engines last longer than U.S.). Suffice it to say, you may be fine by using a convenience-store bought 5-30 if changing every 3k or less...I've needed to do that for years. Otherwise, these U.S.-created thin oils will slowly allow for burn-off and build-up necessary for most of us to use auto-rx and the like because we are just talking about the side effects of using these oils rather than dealing with the real issue.
 
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