AMSOIL low HTHS? and HTHS questions.

[cfromc]

Since finding this site, I've really tried to nail down the "best" oil for my vehicles based on environment, driving style, usage, expectations etc. I'll be changing oil soon on all my vehicles and I'm comparing several brands and a couple different weights and I've noticed that most of Amsoil's offerings have a lower HTHS than the other oils I'm comparing. For example:
Amsoil:
XL 5W-20=2.7
XL 5w30=3.2
XL 10W-30=3.2
ASL 5w30=3.2
ATM 10W-30=3.2
HDD 5w30=3.5

VS.
Pennzoil Platinum:
5W-20=2.7 (same)
5w30=3.7 (.5 higher than most of Amsoil's XW-30s)

Redline:
5W-20=3.3 (.6 higher)
5w30=3.8 (.6 higher than most of Amsoil's XW-30s)

I'd throw more comparisons up but I've already narrowed my search and these were left.

So....why do most of Amsoil's XW-30s have an HTHS of 3.2? Is it because 3.2 is good enough? or, because the other oils lose HTHS and end up at 3.2 or lower yet Amsoil's keeps steady at 3.2? or because HTHS isn't that important? or do the other manufacturers know something that Amsoil doesn't (doubt it, but threw it in anyway).

I've eliminated a couple of oils because of the low HTHS...am I just to worried about HTHS or is it a valid concern to want an oil with an HTHS of over 3.2? I've read previous postings going back 2-3 years and it seems that the higher the performance of the engine, the more important higher HTHS is. But, isn't HTHS important even in engines that don't see WOT/Redline every day due to the temperatures and pressures at the piston rings/cam followers/bearings, etc.?

 

[Bryanccfshr]

Quote:

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.am I just to worried about HTHS or is it a valid concern to want an oil with an HTHS of over 3.2? ?

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Yes you are too concerned. Unless your vehicle specifies a certain oil HTHS is an arbritary number that is not all that important to the majority of vehicles.

Thin is in.

 

[buster]

Bryan is correct. *The PP 5w30 is a typo. Most modern engines do not require high levels of ZDDP and HT/HS oils. Amsoil uses very good additive packages. Don't worry about it.

 

[cfromc]

From my research, mostly on this site, but I've also been looking around the 'net, it appears that an HTHS of less than 2.6 is detrimental to wear, while wear is reduced as the HTHS goes to 2.9 to an "acceptable" level and wear is further reduced (a little) as HTHS goes higher. None of my vehicles have an HTHS spec that I know of but that doesn't mean I want to just use anything. As I'm learning, most things to do with oil represent a trade-off of sorts and this is probably one also but I'd like to feel comfortable with what I'm using. I will probably never know what HTHS is ideal for each vehicle but I'd like to know where the level is for good protection (minimum for GOOD protection, not bare minimum) and where the level is when going any higher does not result in better protection.

 

[cfromc]

Comparing other oils, the PP must be closer to 3.2? Mobil 1 is only 3.09. That's a big typo on Pennzoil's part. I guess Redline is just in a league of their own with the high HTHS. Of course, their oils seem to be on the thick side for their respective viscosity ratings.

 

[buster]

Quote:

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but I've also been looking around the 'net, it appears that an HTHS of less than 2.6 is detrimental to wear, while wear is reduced as the HTHS goes to 2.9 to an "acceptable" level and wear is further reduced

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That is not really the case anymore as additive technology and engine metallurgy improving. I would ignore that test. It's also very dated.

 

[Bryanccfshr]

I know exactly where you are coming from and where and what you have been reading. As do those who mentored me out of that way of thinking.
Here are some threads to read on the matter I Am Tired of Hearing Oil Must Have a HTHS of 2.9 or 3.5 or Whatever

Viscosity Shear (Viscosity reduction and permanent shear)

Hope this helps

 

[cfromc]

So is there a minimum HTHS for good protection? How does metallurgy and the additive package allow a low(er) HTHS to protect an engine? I'm not being facetious, I just thought that HTHS was the ultimate viscosity under high temp/high shear conditions and, after a certain point, the lower numbers did not protect, simply due to the lower viscosity. Also, if you are aware of any recent studies, please point me in that direction.

 

[Bryanccfshr]

I want to note that my position has changed since those postings as I have learned from those discussions. Look at the UOA's and explain how the lower hths 5w20's are hurting the engines.

 

[cfromc]

I read the first thread listed already and I just read the second one, but, I still don't "know" the answer. Let's say, for the sake of argument, that a person could get an oil with all the attributes they wanted and then could choose the HTHS. What would they choose, within reason, say between 2.6-3.8 in increments of .1? (for a XW-20 or XW-30 oil)

 

[Bryanccfshr]

5w20 has a minimum HTHS of 2.6 while 30wts have a minimum of 2.9
If they meet that and you have a vehicle that specifies fuel effecient motor oils the minimum HTHS should be your target.

Personally the differnce between 2.6 and 2.9 really isn't significant IMO so since my two trucks have been freshly back speced for 5w20 I will run the 5w20 I think is the best formulation for the money regardless of HTHS.

All increasing the HTHS does is increase internal friction. A higher HTHS is not desireable for power or economy or protection(friction =heat which goes agianst the oils function as a coolant).

So the question remains. What oil does your engine specify?

 

[Ron AKA]

If you are interested in max HP and gas mileage then you want low HT/HS viscosity, not high. Xw20 should be close to 2.6 and Xw30 close to 2.9. See this thread where the subject gets thrashed to death, but most important read the link in my first post, and you will understand.

Redline Compromises HP & Mileage

 

[cfromc]

Well, I'd rather have some increased friction than increased wear. The information I've seen suggested that wear greatly increases below a minimum HTHS value and I haven't seen any studies to dispute that (yet). Power and mileage are great but I'd also like reduced wear. My manual (for both cars) specs 5w30 as preferred but 0W-30 and 10W-30 as optional depending on temperature. No HTHS spec is given that I've seen. I'd like to try a thinner oil than I'm using, for the reasons you've mentioned but I don't want to go too far. Currently I'm using Amsoil XL 5w30 in one vehicle and ASL 5w30 in the other. One vehicle is mostly short trips and has a 180 degreee thermostat so it generally runs about 20 degrees or more cooler than normal which would seem to point to the possibility of running a thinner 5w30 or a thick 5W-20 or a mix of the two. The only problem is that its forced induction and running about 12 psi at full boost so I'd like to make sure its protected when hot and at full boost. The other vehicle sees more mixed city/highway and frequently gets to operating temperature, it almost never sees full throttle or ultra-high speeds. The short trip vehicle is still under BTB (for another 5K) and the oil will be changed about every 8,000 miles per the OLM. The other is well beyond BTB and the oil will be changed every 10K and adjusted per UOA's.

So, to asnwer your question about what is specified: I take the manufacturers spec into strong consideration but I still want to "fine-tune" it. For example, we know that a 5w30 must be between 9.3-12.5@100 so I could technically be within spec by running an oil that has 9.3 and I might get better power and mileage than one with 12.5 even though they are both 5w30s. Maybe this is off-topic but I've determined what all the other specs I desire, now I just want to fine-tune the HTHS. My idea was to mix two same-brand 5W-20 and 5w30 oils and I've come up with nearly ideal mixes, except the HTHS of the Amsoil mixes seems a little low. Just wanted to get people's opinions about where the cut-off is. I thought it was 2.9. I must say that the HTHS seems to be the hardest attribute to find information on.

 

[Ron AKA]

If you read the article in the Redline link you will understand better. The European car manufacturers were/are hung up on HT/HS, and up until a few years ago specified a minimum of 3.5 or so. So Europeans (and buyers of many of them from Europe) get ridiculously high viscosity oils recommended for them. Along came ILSAC which does not include the Europeans, with the objective to increase gas mileage and cut down on cat converter poisoning. This lead to the GF-4/SM spec which sets a minimum HT/HS for Xw20 at 2.6 and 2.9 for Xw30. They also tightened the gas mileage requirements. So oil mfgs were challenged to keep HT/HS over a certain number but still achieve gas mileage.

If you read the report I posted, you will see that one view is that HTHS should be more than 2.9 to minimize wear. However, if you check the UOA forum here, you will not find issues with those using the 5w20 oils and most will be closer to 2.6.

But, from what you say about your choices, I suspect you will not be convinced.

 

[cfromc]

Ron: I responded to that thread. These are some of the things that concern me, copied from the paper you reference:

"Impact on Durability
Durability in Gasoline Engines
The potential disadvantage of moving to lower viscosity lubricants is the thinner oil film that
is expected to exist between lubricated contacts within the engine. However, it should be
remembered that in Europe, current oils have a relatively high viscosity (>3.5 mPa.s)
compared to those marketed in the US and Japan. The move from oils that have High
Temperature High Shear Viscosities (HTHSV) of 3.5 mPa.s to oils with a HTHSV of 2.9
mPa.s is not expected to have a major effect on engine durability for modern gasoline
engines. Indeed, some of these engines may well be running on 2.9 mPa.s oils in the USA or
Japan. Durability may well be of more concern when moving from oils with a HTHSV of
2.9 mPa.s to lower values (e.g. to 2.6 mPa.s)."

This would seem to indicate that there is a difference in wear when HTHS goes too low.

Also:
"In Europe, the emphasis has been on durability, since very high
speed driving occurs in certain European countries. Therefore, in Europe, until recently,
passenger car lubricants have been required to have HTHSV (high temperature high shear
viscosity, measured at 150°C and a shear rate of 106s-1) greater than 3.5 mPa.s."

I realize the USA doesn't have an autobahn but do I need to worry as I'm keeping up with traffic on the highway during summer that my engine is not protected, even though I'm getting ~1% better fuel mileage?

Besides that, most of the comparisons are between 5W-20 oil and XW-40 oils. I would expect to see some MPG differences between a 20 and a 40. It would be nice to compare a 5w30 to a 5W-20 but I understand why the 40 weights were used. Noted by the author of the paper:
"However, to achieve good fuel consumption, whilst still retaining low deposit forming tendency, good
oxidation stability, good durability control, etc., still requires careful lubricant formulation,
and requires a judicious choice of base oil, additive package and Viscosity Index Improver."
This seems to reinforce that a low HTHS is not the magic bullet.

 

[Ron AKA]

Suggest you check out the 5w20 UOA test results at the UOA forum. Remember that article was written about 2000, very early in the development of the GF-4 standards.

The wear concern is in the valve train, and one should look for iron as the sign. 4 valves per cylinder and roller cams reduce the risk of valve train wear. If you have an old style valve train then you may be wise to keep HTHS at 3.0 or higher.

 

[cfromc]

Agree with the UOAs. I do have two valves per cyl. Looks like I will just try to keep the HTHS between 2.9 and 3.2.

 

[goodvibes]

Different horses for different courses. I wouldn't use a thin oil in a BMW or Audi. The motors were built with A3 in mind and it doesn't just relate to high RPMs. The Bearing are probably toleranced for that spec. High load low RPM wear could also be sacrificed with the wrong spec. Hardly ridiculous.

 

[goodvibes]

I think that you'll find that lower HTHS oils do show more wear on certain vehicles in UOAs.

 

[Pablo]

Great discussion fellows. The thing I find a bit ironic is the fact that Amsoil used to build several of the listed oils (the PAO oils ASL, ATM) on the thick, higher HTHS side - of course the main complaint was not wear or shearing, but rather the thickening.

I don't think there is a magic HTHS number where wear increases as can be at least anecdotally verified by UOA's, but as goodvibes says - some cars do benefit from at least a higher stable viscosity. The recommendation is to go with the XW-40's in Amsoil's line-up for some of the Euro cars.