HT/HS, lower = slightly better fuel economy BUT

[Drew7a]

Quite interesting that discussions of lower HT/HS always center around improved fuel economy, but never mention increased or equal longevity of engines or reduced wear compared to high HT/HS.

Older video:

Impact of High Temperature High Shear (HTHS) Viscosity

One of the ways to achieve these is through the use of lower high temperature high shear (HTHS) viscosity engine lubricants, alongside more modern engine design.

360.lubrizol.com

 

[ZeeOSix]

There are plenty of sources that mention that as the HTHS viscosity goes down, so does the "film thickness" (ie, MOFT) and therefore the higher likelihood of increased wear.

From the article above, this is a key sentence:
"The move to lower HTHS viscosity engine lubricants requires design, development, and formulation changes, where performance additives and performance polymers have a key and fundamental role."

This means as the viscosity (and HTHS) goes down, the "film thickness" also goes down, and therefore the "film strength" produced by AF/AW additives needs to be better in order to help mitigate wear that results when the film thickness due to viscosity can't do it's job as well. When the film thickness breaks down and more metal-to-metal contact occurs, the AF/AW additives need to take over to help mitigate the wear.

The Importance of Lubricant Film Strength

Discover why film strength is one of the most critical lubricant properties for protecting a machine’s internal components.

www.machinerylubrication.com

 

[FZ1]

There are plenty of sources that mention that as the HTHS viscosity goes down, so does the "film thickness" (ie, MOFT) and therefore the higher likelihood of increased wear.

From the article above, this is a key sentence:
"The move to lower HTHS viscosity engine lubricants requires design, development, and formulation changes, where performance additives and performance polymers have a key and fundamental role."

This means as the viscosity (and HTHS) goes down, the "film thickness" also goes down, and therefore the "film strength" produced by AF/AW additives needs to be better in order to help mitigate wear that results when the film thickness due to viscosity can't do it's job as well. When the film thickness breaks down and more metal-to-metal contact occurs, the AF/AW additives need to take over to help mitigate the wear.

The Importance of Lubricant Film Strength

Discover why film strength is one of the most critical lubricant properties for protecting a machine’s internal components.

www.machinerylubrication.com

This^^^^^^^so I stay on the "thick" side of my car's grade ( 0w-20). PUP very quiet and smooth in my 17 Camry.

 

[PimTac]

Quite interesting that discussions of lower HT/HS always center around improved fuel economy, but never mention increased or equal longevity of engines or reduced wear compared to high HT/HS.

Older video:

Impact of High Temperature High Shear (HTHS) Viscosity

One of the ways to achieve these is through the use of lower high temperature high shear (HTHS) viscosity engine lubricants, alongside more modern engine design.

360.lubrizol.com

How would one track that or prove it? That is the difficulty.

 

[wpod]

Who has worn out a properly maintained engine?

 

[ZeeOSix]

Just because the engine didn't blow-up or stop running doesn't mean it wasn't more worn. "Worn out" can mean a lot of things depending on who's defining the term. If formal studies and testing shows a correlation between HTHS and wear, then that's what can also be going on in engines running around on the streets.

 

[weasley]

Just because the engine didn't blow-up or stop running doesn't mean it wasn't more worn. "Worn out" can mean a lot of things depending on who's defining the term. If formal studies and testing shows a correlation between HTHS and wear, then that's what can also be going on in engines running around on the streets.

But studies tend to use the same test for different oils. The point above is that lower HTHS oils are generally specified for engines that have been designed to accommodate them - so don't go putting lower HTHS oil in older engines and if you put higher HTHS oils in newer engines you may improve wear above the accepted service levels but at the expense of fuel economy.

 

[Drew7a]

There are plenty of sources that mention that as the HTHS viscosity goes down, so does the "film thickness" (ie, MOFT) and therefore the higher likelihood of increased wear.

From the article above, this is a key sentence:
"The move to lower HTHS viscosity engine lubricants requires design, development, and formulation changes, where performance additives and performance polymers have a key and fundamental role."

This means as the viscosity (and HTHS) goes down, the "film thickness" also goes down, and therefore the "film strength" produced by AF/AW additives needs to be better in order to help mitigate wear that results when the film thickness due to viscosity can't do it's job as well. When the film thickness breaks down and more metal-to-metal contact occurs, the AF/AW additives need to take over to help mitigate the wear.

The Importance of Lubricant Film Strength

Discover why film strength is one of the most critical lubricant properties for protecting a machine’s internal components.

www.machinerylubrication.com

"There are plenty of sources that mention that as the HTHS viscosity goes down, so does the "film thickness" (ie, MOFT) and therefore the higher likelihood of increased wear."

This is exactly what I was alluding to. Read my post again. The lower the HTHS the potential for more wear, if there was less wear they would be touting it, you would see statements like "Improved fuel economy and prolong engine life with low HTHS oils". But my point is you never see this type of statement instead you always hear of a potential increase in fuel economy."

Yes, you can design an engine to use lower HTHS oils but the point being all things being equal, the lower the HTHS the potential more wear.

 

[kschachn]

Yes. There are no technical advantages a to lower HT/HS other than fuel economy.

 

[RDY4WAR]

Yes. There are no technical advantages a to lower HT/HS other than fuel economy.

In daily commuters, yes. Though they are the extreme exception, some race engines with very thin, low tension rings don't like high HTHS oils. The thicker oil film and increased hydrodynamic friction can upset ring seal, increasing blow-by, and increasing oil transport into the chambers causing detonation and other issues. There's also power that's affected which has been seen on a dyno to show up to 1% power loss per oil grade. Again, not a big deal for a daily driver, but to a class racer, a 1% change in power is HUGE! That's mostly from hydrodynamic friction in the bearings, becoming an exponentially greater factor as rpm increases.

We have to also consider what accompanies a higher HTHS. Comparing a 2.6 cP and 3.0 cP wouldn't be a big deal, but say we're talking about 4.0+ cP. At that point, you're getting into higher viscosity base oils and with that comes decreased solubility resulting in decreased additive response and cleaning ability, higher specific heat capacity allowing the oil to run hotter and more difficult to cool down, and increased aeration/foaming risk.

You probably get to a point with any engine where the increased friction and higher specific heat of the higher viscosity/HTHS oil leads to increased temperature to where the viscosity and film thickness is about the same as the lower viscosity/HTHS oil at a cooler temperature. Which brings up the question of how oil capacity and cooling impacts things. If a 0W-20 (2.6 cP) oil is running 220°F, which would have more benefit? Going to a 0W-30 (3.0 cP) or adding a small cooler to bring temps down to 200°F? At which point do the lines of temperature additive activation, HTHS/film thickness, etc.... all cross to create the perfect atmosphere. Then it probably changes for every engine and even among the same engines with different driving styles.

 

[FZ1]

No significant mpg loss in, my experience, going from 2.3 to 2.6/2.7 in my 0w-20 2.5 Camry. In fact I gain mpg and smoothness with 2.6/2.7 vs. lower HTHS. I attribute this to better ring seal/more efficiency with moderately higher HTHS. One has to have enough HTHS to fully seal the rings for max efficiency. I will only run "thick" (8.8 vis) 20 grades. YMMV

 

[FCD]

I always run A3/B4 oils.

 

[Bill_W]

Does VII give better fuel economy?

https://www.jstage.jst.go.jp/article/trol/14/5/14_404/_pdf/-char/en

 

[sk_pete]

Quite interesting that discussions of lower HT/HS always center around improved fuel economy, but never mention increased or equal longevity of engines or reduced wear compared to high HT/HS.

Older video:

Impact of High Temperature High Shear (HTHS) Viscosity

One of the ways to achieve these is through the use of lower high temperature high shear (HTHS) viscosity engine lubricants, alongside more modern engine design.

360.lubrizol.com

really worth the hassle?

startstop, thin oils, any other horse , are just to please the green puppets (and fleet owners); not you or any other private car owner.

i had to pour organotungsten(molygen) into stealership´s total 0w30 lowsap(expensive), otherwise it would be like can of nails.
but still any 5w40 makes it quieter.

 

[ZeeOSix]

But studies tend to use the same test for different oils. The point above is that lower HTHS oils are generally specified for engines that have been designed to accommodate them - so don't go putting lower HTHS oil in older engines and if you put higher HTHS oils in newer engines you may improve wear above the accepted service levels but at the expense of fuel economy.

Yes, and to add, only engines there are specifically designed for lower viscosity oil are ones that specify 0W-8 (coming here too soon I'd bet) and 0W-16. That's why there is an ILSAC GF-6A and GF-6B spec now for 0W-16 and everything else above 0W-16.

Lots of engines were back speced down to xW-20 with no redesigns, due to the goal of getting more CAFE credits. Doing that may have still been "within acceptable wear limits", but it doesn't mean there wasn't more wear ... just not enough to break the limit. Still a fact that higher viscosity equates to more film thickness and more protection headroom to prevent wear.

 

[wemay]

0W-20 = slightly more wear and i'm just fine with that when using it.
5W-30 = slightly worse mpg and i'm just fine with that when using it.

 

[Bill7]

I've read a post on the toyotanation site on 0W-16 being speced for 2018+ Toyota Camry's. They have photos of the Toyota owner's manuals in Europe and Australia for the same engine specing 5W-30. High Temperate / High Sheer (HTHS) is connected with engine wear protection. The lower HTHS numbers the more engine wear. The HTHS numbers for 0W-16 are scary. Even the HTHS from 0W-20 are borderline.

From Pennzoil on 0W16 Oils.

www.toyotanation.com

When Ford switched from 5W-30 to 5W-20 years ago, they had a huge problem with increased timing chain wear.

The whole move to thinner oils is not to improve engine protection. Instead it's to save automakers money by reducing fines from the EPA over CAFE. The benefit in fuel economy is not measurable on an individual car, but the tiny fraction adds up over a fleet of hundreds of thousands of cars. The automakers don't care about engine wear after the car's warranty expires. They only care about avoiding the CAFE fines.

Thiner oils have much lower HTHS numbers. Thin oil's achilles heal is higher engine temperatures. Higher temperatures can occur when idling the car for extended periods on a hot day with the air conditioning on when the car is parked. Also, during extended stop and go driving on a hot day with the air conditioning on. Engine temperatures rise higher even with a healthy coolant system.

I understand and respect those people following their owner's manual recommendation on the ultra low viscosity oils 0W-16 and even 0W-20.

The best thing about car ownership is that you are the captain of your own ship, and you can make your own decision about which oil protects your engine the best.

I like to keep my cars for a very long time. I'd like to get 300k miles out of my cars, and protecting the engine is my primary concern.
After reading the entire toyotanation thread, and also after reading about the Ford Timing chain wear due to the switch to from 5W-30 to 5W-20,
I've decided to only use 5W-30 synthetic in all of my vehicles for better protection of the engine. It's such a great feeling of independence to ignore CAFE and it's forcing of automakers to go to thin oil at the expense of engine wear. It feels like July 4th, Independence Day!

 

[ZeeOSix]

"There are plenty of sources that mention that as the HTHS viscosity goes down, so does the "film thickness" (ie, MOFT) and therefore the higher likelihood of increased wear."

This is exactly what I was alluding to. Read my post again.

I know what you were saying, and I mentioned what I did because you said in the info you posted that the info source didn't mention that lower HTHS has the potential to cause more wear. Maybe they don't want to mention it so it doesn't scare people from using lower viscosity oil to obtain slightly better fuel mileage.

 

[Drew7a]

From a 2022 European Honda Civic Manual

Notice the *1 Formulated for better Fuel Economy. Just another data point.

 

[Drew7a]

The 2016 you could use everything under the sun.

I did not know that 20 grade could meet A3/B3