Where Did the Notion Come From that Oils with HTHS Below 3.5 Were Unacceptable for Wear Control?

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This study discussing wear as a relative function of viscosity is w.r.t. the bearings, correct? Not the pistons/liners?
 
This study discussing wear as a relative function of viscosity is w.r.t. the bearings, correct? Not the pistons/liners?


Correct. The focus of this study was on the bearings alone.

Also note that this study was date 1998. The comparison included bearings with a lead component which nobody uses anymore in passenger automobiles.
 
Correct. The focus of this study was on the bearings alone.

Also note that this study was date 1998. The comparison included bearings with a lead component which nobody uses anymore in passenger automobiles.
That, and no one drives around with their sump perpetually at 304 degF while running 6,000 rpm with an unbalanced load on the crankshaft ... the test conditions used to bring out the HTHS importance.

But hey, it's a SAE "study" that "proved" HTHS is important ... 25 years ago, under the most inane unrealistic conditions.
 
And for no reason at all, modern cars started burning oil and destroying timing chains.
What is interesting and often forgotten is the computer cars with more precise fuel metering and timing via knock sensors are what allowed the thinner energy conserving oil and good engine life but as in all things we are finding the weaker links. Cujet nailed it again.
 
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Worried about thinning of the fuel and increased wear? Read: Biodiesel Impact on Wear Protection of Engine Oils, Fang et al., 2007-01-4141.

Here we are lab testing with methods such as the 4 Ball test scar using varieties of diesel fuels. One reason was to test aged vs fresh fuel and wear. Interesting that aged fuels of 5% added to the lubricant resulted in more wear but fresh fuel actually decreased wear. Go thin???

Ali
 
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But they are still recommending 15W40 in Sri Lanka and Lichtenstein, so there’s that. Those engineers are a slippery bunch.
From the Austrailia owner manual screen images I've seen posted on BITOG, Australia owners manuals are recommending 0W-16, 0W-20, 5W-30, and sometimes 5W-40 on the same page, leaving it up to the owner to choose one of those recommended viscosities.
 
From the Austrailia owner manual screen images I've seen posted on BITOG, Australia owners manuals are recommending 0W-16, 0W-20, 5W-30, and sometimes 5W-40 on the same page, leaving it up to the owner to choose one of those recommended viscosities.
Clearly one size doesn't fit all, and the engine won't self destruct with a "thicker oil" in the sump as some would like you to believe.
 
I have actually learned something here. Again, I will still look for as thin an oil as I can get during the start up period (kinematic viscosity). This is because I feel it is best to get more flow before my engine goes into bypass. And I like high RPM. At my usual start up my oil is in bypass at 3,000 RPM by the time I get out of my neighborhood (redline = 9,000 RPM). I feel oils with a HTHS of say 2.5 is fine for my engines.

So the mission will be to find the lowest viscosity at 40C while the HTHS is around 2.5 or so. Looking for a 30 or 40 or 50 grade oil, as many seek, is not in the equation. Now I feel those numbers are essentially useless. Higher grades do not necessarily guarantee higher HTHS, you have to look at the actual specs (as many here already do). I do think that insisting it is >3.5 is unnecessary. The real number, and it has headroom in my book, is 2.5. I reserve the right to lower this number with forthcoming oils however...

I do think the data has some value. It indicates that HTHS is something to look at. I admit this. But I believe that a HTHS of 1.8 or even 1.6 is probably OK for most modern engines using modern lubricants. Though personally I might go for slightly higher values as my cars often have fuel dilution issues.

Ali
HTHS of 2.6 is a sweet spot, which is where 0W-20 oils start out as virgin oils, and which seem to have widespread support on this forum as being safe for long term use. You might be right about HTHS > 3.5 as being unnecessary.
It depends what your goals are. In my case, I'm trying to reduce engine wear to absolute 0, as I plan to keep my cars for decades and hundreds of thousands of miles, and I don't like my engines having oil consumption issues (caused by wear), as that takes away all the fun of having a perfect engine.

In your case it seems you want maximum horse power and fuel economy offered by the thinest oil possible.
There is no right or wrong answer here, it's based on each owners priorities.
 
I do not want any wear either. I have shown that 20 and 30 grade oils in a Ferrari Enzo results in essentially no wear (no track use though). The spec'ed oil is a 10W60. The testing was with engine analysis and oil analysis.

Ali
 
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People often think of viscosity as - 20, 30, 40 and 50 when in reality it's 21,21,23,24....

You can find some 20 grades that have a HT/HS of 2.8-3.2.
 
Also 5W-30 oils are no panacea, as most of them have gotten so thin nowadays that they are just slightly thicker than 5W-20 oils.
So, if you happen to want thick oil, you really need to read the data sheets of each oil on the oil manufactures website.
For what it's worth, my 2 favorite oils (which you can buy in 5 quart jugs on Amazon for 26 to 28 dollars) are:

Pennzoil Platinum Full Synthetic High Mileage 5W-30 with Kinematic Viscosity @100C = 11.4 and HTHS about 3.1 or 3.2
Castrol 5W-30 Euro A3/B4 oil with HTHS = 3.5
 
You're obviously a "thick oil" guy, ?Bill. Relax it a bit. (humor intended).

Ali

PS - I think I am getting less serious with my advanced age.
 
I do not want any wear either. I have shown that 20 and 30 grade oils in a Ferrari Enzo results in essentially no wear (no tack use though). The spec'ed oil is a 10W60. The testing was with engine analysis and oil analysis.

Ali
I'm not sure oil analysis from companies like Blackstone is really that accurate.
Even though it's cost prohibitive, would be interesting to have an ASE certified mechanic open up an engine and check the wear on the piston rings, crankshaft, camshaft(s) and bearings.

Someone who I trust on youtube is "The CarCareNut" channel, which is a Toyota Master Diagnostic certified mechanic who worked in Toyota dealerships in Chicago for over 10 years and is 100% loyal to Toyota. He is oil viscosity agnostic. He recently had a video where he bought a 2022 Toyota Camry for personal use speced for 0W-16 and he is using 0W-16. He also uses the low efficiency Toyota oil filters. He says he's rebuilt over 100 Toyota engines over the years due to excessive oil consumption. To him, the root cause of all the oil consumption issues Toyota has had over the last decade is the 10k mile oil change interval.

His strong conviction advise is to change oil every 5k miles or 6 months whichever comes first.
That is a point many BITOG posters seem to ignore, as Blackstone labs seems to write in all their analysis paragraphs that oil is fine at 10k and next oil change you should stretch to 12k oil change intervals. So I honestly don't put much importance on oil analysis reports.
 
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From the Austrailia owner manual screen images I've seen posted on BITOG, Australia owners manuals are recommending 0W-16, 0W-20, 5W-30, and sometimes 5W-40 on the same page, leaving it up to the owner to choose one of those recommended viscosities.
Well dang what are people on the Internet gonna have to argue about now? Thanks Toyota. Inconsiderate.
 
FYI, I used Dyson Analysis, never Blackstone. Though I am going to use them very soon for a non critical analysis. I paid maybe 5 times as much for a proper analysis. Terry no longer does work for the general public but I can use him as a long time "friend". I am working on experiments with my Ferrari 812 Superfast. For that it is Terry Dyson testing.

This weekend I am going to change the 0W5 oil out of the truck and go to a thick oil - 0W16. The oil will be sent to Blackstone, good enough.

Ali
 
Before it was total'd in a wreck, my wife's 2005 Grand Marquis would beg to differ. After a quater-million miles, the engine ran great, had no major maintenance issues, and didn't consume oil. My 2007 Grand Marquis also did just as well.

The ol' 4.6L mod-motor is very easy on oil in the 2v configurations. All on 10k mile OCIs, 5w-20, mostly conventional oil. Some engine designs are very robust, some not. 281 cubes with only 225 hp doesn't exactly qualify as high-stress ...
The "dino" oil in this UOA series was the Rural King brand; about as cheap an oil as one could buy back then. I'm sure it's HTHS rating was not impressive by any means, though I'm not sure what the actual value would be, but at $1.29/qrt, there little reason to think it was "robust" oil. And yet, it did a fine job protecting the engine, even out to 10k miles repeatedly.

I've seen 5w-20's all the way up to 10w-40's all do well in the old Ford mod-motors (2vs). That engine series just isn't susceptible to viscosity/HTHS concerns in normal use. That engine series could not care less what lube is used, as long as it's reasonbly appropriate for the application. Clearly, some "thin" oils do quite well in some "good" engines.

However, a poorly made lube in a poorly designed/built engine will never end well. There are other engines that don't fare well at all, regardless of what oil is in the crankcase. Some are just trouble prone. And no amount of HTHS would save them.


As both lubes and engines have improved over the years, I think the HTHS topic has lost some of it's zing; it's just not as important as it was decades ago.
Time fixes all. Instead of looking for oil to fix hardware issues maybe some here should concentrate their minds on choosing reliable engines.
 
Time fixes all. Instead of looking for oil to fix hardware issues maybe some here should concentrate their minds on choosing reliable engines.
I was surprised to learn that most supercars regardless of brand never make it to 100k miles. The Quality and QA testing just isn't there, with so many parts made of cheap plastic and even the car bodies getting severed in half in minor car accidents. And fixing even the simplest things like replacing most parts requires dealer sold OEM parts, which instead of costing a few hundred dollars cost 7,000 dollars. You would think if you're going to spend $200,000 on an Italian super car, you should get a high quality car that will last longer than a cheap Japanese economy car costing 1/10 the price. But the opposite is true. So if I could ever afford to buy a super car, it would be an Acura NSX, so that at least you would get Honda's reliablility instead of some Italian supercar maker's reliability. If you google: What is the cost of an oil change for a Bugatti Veyron, the answer is $21,000 for the oil change. For the price of that oil change, you could buy a new Honda Civic or Toyota Corllla and get the whole car. Even if I were a billionaire, I think I'd pay my local mechanic $30 for his labor and give him 5 quart jug(s) of synthetic oil and Fram Ultra oil filter bought at Walmart.

It's also interesting to note that in the latest Consumer Reports Magazine, Mercedes Benz is dead last of all car model brands in reliability.
So with Mercedes, you pay astronical prices for low quality, little to no quality assurance testing, with astronomical parts prices.
I suspect this is intentional, as Mercedes can lessen their cost in making a new car (both parts, research, and Quality assurance) to the lowest cost to Mercedes it could possibly be to build it, and then to sell the car to consumers at astronomical prices based on some misplaced and outdated reputation of quality, and then to allow dealers to astronomically price gouge on the parts and the servicing. So maximum profit for Mercedes and their dealers, and minimum quality to the consumer. That is really a shame, as Mercedes could have taken the high road and actually produced cars that can go to 400k miles like they used to in the 1980's and 1990's.

Consumer reports says Toyota/Lexus remain the top 2 most reliable car brands for many years running.
But to me, Toyota's bland styling and handling are blockers, so I prefer Honda's myself as they are fun to drive and have nimble handling.
 
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Getting back to the OP's question of:
"Where Did the Notion Come From that Oils with HTHS Below 3.5 Were Unacceptable for Wear Control?"

I think the standard came from the European automakers like Mercedes, BMW, and Volkswagon who influenced the ACEA specs.
The reasons are likely that European engine designs run hotter and with more internal extreme pressures than other company's engines.
Also since many of these cars will be run on the Autoban over 100 MPH at high engine temperatures / High RPMs for extended periods, you need the highest level of wear protection.

But I look at HTHS = 3.5 as a plus, as if it provides superior wear protection, why not use it for your daily driver.
No need to settle for adequate protection if you can have superior wear protection, since many of us drive our cars under heavy load / severe operating conditions. To me, there is no need to rally against HTHS=3.5, and denounce it. Instead, embrace it. Getting the highest engine protection is something that will benefit everyone.
 
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