What is HTHS ?

[Fuzz1]

My car (Ford Fiesta Zetec S TDCi Turbo Diesel )requires an oil that has a low HTHS. What does this mean ?

This spec conforms to all Ford WSS-M2C913B and WSS-M2C934 oil specs.

Can someone also please elaborate on the Ford WSS-M2C913B and WSS-M2C934 oils specs and what they mean.

 

[ZZman]

High Temp/Low Shear

Low HTLS would give better efficiency or MPG. High HTLS gives more durability.

This is a pretty good read: http://www.atiel.org/members/pdf_files/ACEA Stow.pdf

 

[Fuzz1]

Awesome , thanks ZZman

So low HTHS will not last as long as a oil with high HTHS.

Wouldn't it be better to use an oil with a high HTHS if I wish for my engine to last longer ?

I also noticed that ACEA C1 oil cointain no TBN. Am I reading your link correctly ???

 

[dailydriver]

YES!
I for one would NOT sacrifice oil life/longevity (and possibly engine life/longevity) for the sake of saving only 1/2 to 1 kilometer per liter of fuel.
Especially in the possible fuel diluting environment of a boosted oil burner!! I would think that one wants the highest possible HTHS & TBN in that scenario, but I could be wrong.

Hopefully the 'experts' will chime in with their insights.

 

[wujek]

Btw, anyone knows GC's HTHS? Not listed in the GC's specs online....

 

[Fuzz1]

Thats what I was thinking dailydriver. Why would Ford recommend such a spec though.

BTW , my TDCi is planned for a remap next month which will increase the fueling and boost quite a bit... hence my concern.

I am currently using Delo 400 15w40 but would like to use a fully synthetic oil. Fully synthetic HDEO's are to hard to find here in SA.

I purchased Total Quartz 9000 5w40 the other day and will give that a go , but I was thinking of using MOBIL 1 0w40

 

[7TFord]

Kind of confused by this low/high HTHS designation. I'm usng Motul's Eco-nergy 5/30...

http://www.gprparts.com/brands/motul/motul8123.asp

...in my 4.7L 4Runner because it calls for an "SL" rating. The product info at the link suggests this oil will protect my engine more than enough as Motul is a quality product, but also that it may be unsuitable for some. I definitely can't find any info in my manual or otherwise that states my engine requires a low HTHS lubricant, only the "SL" classification. I'm wondering what they mean by unsuitable? Does the lack of "durability" mentioned for low HTHS lubricants only mean not for extended drain intervals?

 

[ZZman]

No manufacturer really cares about durability as long as the car gets past the warranty. Do they really care if you can go 200,000 miles? They are more concerned about fuel economy.

I also wonder if this has to do with the lowering of zinc to help prolong Catalytic converter life.

 

[bruce381]

""High Temp/Low Shear"" ?????

HTHS is High Temp High Shear is a test method to mesure oil vis under "High Temp High Shear" conditions that would be useful in a engine such as valve train or bearing areas.

There is a Minimium HTHS vis for most multi grade oils there is NO maximium though so a oil could be a 5/30 and be way high in HTHS vis which would/may/could affect MPG
bruce

 

[MGregoir]

2.6 for 20 weight, 2.9 for 30 weight, as well as 0W-40, 5W-40 and 10W-40, 15W-40 as well as 50 and 60 weight oils have a minimum of 3.7.

HDEO is generally a minimum of 3.7 and as high as 4.5, most European cars are 3.5, and 2.6 is considered the minimum level for decent wear protection.

 

[widman]

It seems to me that they are looking and specing the oil by the shear rate rather than the traditional viscosity ratings, thereby classifying low as 2.6 to 2.9, and high as over that.

I'd GUESS that this is to get a specific cP in the bearings and other places under pressure in spite of what base oil and viscosity grades you are using. In other words, just because a 5W-40 pumps as well as a 5W-20 in cold weather, they don't want the 4.4 cP that the 5W-40 probably gives you in the HTHS.
Sort of goes against the common thought that as long as you get the oil flowing, thick is better when it is hot. I guess that means they don't want a 5W-50 either.

 

[Fuzz1]

Sooooooo , if I am reading correctly , you guys are saying that an oil with a low HTHS has a low viscosity under high temperatures where higher sheer rates are experienced and is only and indication of flow rather than protection or sheering resistance of the oil itself ????

Sorry , I need to clear this up ASAP as I have a batch of Q8 5w30 Low HTHS ACEA B5 / C1 (Ford WSS-M2C913B and WSS-M2C934) oil on order

 

[MGregoir]

At higher temperatures, where HT/HS is tested and how it is tested (in a bearing) it is used to test the performance of the oil under high shear conditions in engine hot spots such as bearings, etc.

If your manufacturer says to use an oil, I would not worry all that much, higher HT/HS can protect certain areas of the engine better (kinematic viscosity relates more to flow, which is where the 5W-30 comes from) at the expense of fuel economy.

 

[MGregoir]

The A5/B5 oils match the SAE requirements for grade, XW-20 is 2.6 and XW-30 is 2.9. A3/B3 is 3.5.

 

[fitzski]

Originally Posted By: ZZman
No manufacturer really cares about durability as long as the car gets past the warranty. Do they really care if you can go 200,000 miles? They are more concerned about fuel economy.


Of note... the last page of your posted PDF states:
Quote:
Fords key lube oil goals lie in:
- aftertreatment compatibility
- fuel economy
- long drain capability
- volume


But... what about protecting the engine?!

 

[FrankN4]

High-Temperature/High-Shear

This test is a simulation of the shearing effects that would occur within an engine. In fact, it's actually designed to simulate motor oil viscosity in operating crankshaft bearings.

Under high stress conditions where shearing can occur, the VI Improvers (polymers) break down. As they do, the viscosity of the oil decreases. This is what the High Temperature/High Shear test checks for.

The HT/HS test is measured in Centipoise (cP) as the Cold Crank Simulator test is. However, in this case, because you're hoping for the least loss of viscosity with an increase in heat and stress, you want the cP value to remain high.

Each SAE multi-viscosity grade has a specific lower limit for the HT/HS cP value. If a multi-viscosity oil cannot achieve a cP value above that limit, it cannot be classified under that viscosity grade. For instance, according to the SAE specifications, an oil must achieve an HT/HS cP value of 3.7 or higher in order to be classified at the 15w40 viscosity grade. The thinner the oil the lower the number.

So, whether this data appears on a manufacturer's tech spec sheets or not, the company always has the data and it should be available on request.

I do not remember where this came from but it is not from me. Someone else deserves the credit.

I run Mobil 1 15W-50 with a HTHS of 4.5. My Toyota has 300,000 miles and engine is still smooth, quiet, and powerful. I run the same oil in my Chevrolet Cavalier 2.2L 4 cyl and it now has 202,000 miles. Again, engine runs great, smooth, powerful, like a new engine.

I have nothing but doubt about improved gas mileage with a much thinner oil. I get as good as and sometimes better gas mileage with the 15W-50 as some people get in the same vehicles with a 0W or 5W-30. My 2008 Chevrolet Silverado only has 1900 miles and I changed oil and filter at 500 miles. On two trips since I have had it, it got 23 MPG and 21 MPG. 21 MPG was across the Smokey Mts with a full camping compliment. EPA estimate said some people would get as much as 23 MPG with a 5W-30. When this truck gets to about 10,000 miles, I expect 25 MPG will be common.

Go with the best/highest HTHS you can get and protect your engine and give you peace of mind. The difference in real world, daily driven fuel economy doesn't exist or I guess I should say no one has ever been able to even demonstrate it to me let alone prove it.

If you never drive more than 5 miles one way to work or whatever, I would assume a low HTHS would give better fuel economy but it will still be reduced because the oil will never come up to temp and even a 0W-20 oil is going to be thick, just not as tick as a 5W,10W, 15W-XX.

 

[Ken2]

Originally Posted By: 7TFord
I'm usng Motul's Eco-nergy 5/30...
http://www.gprparts.com/brands/motul/motul8123.asp
...in my 4.7L 4Runner because it calls for an "SL" rating.


This is meaningless. SL has been superceded by SM. If your manual was re-written today, it would call for SM oil--and that is exactly what the 4.7 engine of today uses and what the dealership would put into your engine.

HTHS viscosity is a very different measure than the kinematic viscosity measures in centiStokes. HTHS gives a much more realistic measure of what happens to the oil in the engine. Kinematic viscosity is merely the time it takes a quantity of the oil at the specified temperature to flow through a certain orifice. With the modern viscosity index improvers and other additives, this is not the best measure of how the oil reacts in service.

In some cases the engine maker will specify an oil for low pumping and friction losses inside the engine to save fuel which is also the right oil to protect the engine. This is what we see in the trend to lower viscosities including lower HTHS viscosities. A higher vis oil might give longer engine life, or the engine life with the lower vis oils might be as long as the life of the rest of the vehicle.

 

[TeeDub]

Ken,

Exactly the point I've been trying to make on another fuel efficiency thread....

HT/HS viscosity is inversely proportional to fuel efficiency. I don't think this is a linear relationship - more like 1/ square root or cube root of the HT/HS viscosity is proportional to F.E.

 

[Shannow]

TeeDub, I remember quite clearly being kicked around (not by you) for suggesting that HTHS probably made more difference to economy than visc @ 100C.

 

[7TFord]

Originally Posted By: Ken2
Originally Posted By: 7TFord
I'm usng Motul's Eco-nergy 5/30...
http://www.gprparts.com/brands/motul/motul8123.asp
...in my 4.7L 4Runner because it calls for an "SL" rating.


This is meaningless. SL has been superceded by SM. If your manual was re-written today, it would call for SM oil--and that is exactly what the 4.7 engine of today uses and what the dealership would put into your engine.

HTHS viscosity is a very different measure than the kinematic viscosity measures in centiStokes. HTHS gives a much more realistic measure of what happens to the oil in the engine. Kinematic viscosity is merely the time it takes a quantity of the oil at the specified temperature to flow through a certain orifice. With the modern viscosity index improvers and other additives, this is not the best measure of how the oil reacts in service.

In some cases the engine maker will specify an oil for low pumping and friction losses inside the engine to save fuel which is also the right oil to protect the engine. This is what we see in the trend to lower viscosities including lower HTHS viscosities. A higher vis oil might give longer engine life, or the engine life with the lower vis oils might be as long as the life of the rest of the vehicle.


I agree. The manual for our 08 Yaris Sedan calls for an SM oil but oddly enough the filler cap still denotes an SL standard. I guess they don't make new caps as often as they print manuals. The bottom line I guess is I chose the Motul product for my 4Runner as it is a quality lubricant and isn't likely to detonate my Lexus born 4.7 motor low or high HTHS, and if I get a few more mpg's so be it. I certainly don't want a 15/50 in there!

I'm still curious though as to the statement at the above link?

"These oils may be unsuitable for use in some engines"

Curious as to the definition of "unsuitable"? There are actually engines that these oils will harm? There is no mention in my 06 4Runner manual or the manual for the 08 regarding HTHS and I'm pretty sure there isn't even anything on the Motul containers I have either.