Worn Engine - 0w-40 or 5w-50 for Max Longevity?

[CATERHAM]

Originally Posted By: mechtech2
Garnet -
HTHS = High Temperature High Shear.
There is a rating for each oil, just like viscosity.
2.6 to 3.8 is a range for common oils.
Guys around here don't like lower HTHS #s, but engines are not throwing rods because of it.
Sure, more data is always valuable, but I think this one is over valued.


Not true.

HTHS is a measure of viscosity under pressure, measured in centiPoise (cP), and taken at a temperature of 150C.

It competes with the more common and much less expensive kinematic viscosity measurement taken at 100C and measured in centistokes (cSt). This measure of viscosity is made by measuring the time it takes for a steel ball to fall under the force of gravity through a column of oil.

In an engine the "Operating" viscosity is under pressure and therefore correlates well with the HTHS viscosity measure even at normal operating temperatures. The same cannot be said for the kinematic 100C viscosity measurement.
In other words, oils with similar HTHS viscosity spec's will have similar operating viscosities in an engine at oil temps as low as 70C although their 100C k'vis spec's may be markedly different.

In comparing oils, just because one oil has a higher 100C k'vis spec' doesn't mean it will necessarily have a higher operational viscosity unless it's HTHS vis is higher as well.
Knowing the 100C k'vis spec' of an oil is a good starting point but the bottom line is it's HTHS vis spec'.

 

[Gannet167]

Ok, this is off Shell's website (Strangely, they also have Pennzoil and Quakerstate info in their library, hmm)


SAE Viscosity Grade T5 0W-40
Kinematic Viscosity (ASTM D445) @
40°C mm2/s 85.8
100°C mm2/s 15.0

Dyn. Index (ASTM D 5293)
@ -35°C mPa s 5800
Viscosity Index (ASTM D2270) 185
Total Base Number mgKOH/g (ASTM D2896) 9
Sulfated Ash % (ASTM D874) 1.2
Density @ 15°C kg/l (ASTM D 4052) 0.844
Flash Point (COC) °C (ASTM D92) 230
Pour Point °C (ASTM D97) -48

So, is that good?

 

[Gannet167]

Found here http://www-static.shell.com/static/can-en/downloads/shell_for_businesses/oils_lubricants/1-54.pdf

 

[Jim Allen]

Well and concisely stated!

 

[CATERHAM]

It's unfortunate that Shell doesn't provide the HTHS vis spec'.
If you're interested in this oil I would contact Shell to try and get the HTHS vis spec'.

What I can say is that this is a high VI oil which tend to have relatively low HTHS viscosities relative to their 100C k'vis spec which is fairly high at 15 cSt. If I had to make an educated guess I'd say the HTHS vis would be around 3.8 cP to 3.9 cP.
By comparison Pennzoil 5W-40 has a HTHS vis of 3.7 cP as does M1's 0W-40.
Therefore I suspect the Shell oil will be somewhat heavier if that's what you want.

 

[il_signore97]

Originally Posted By: Gannet167
Ok, this is off Shell's website (Strangely, they also have Pennzoil and Quakerstate info in their library, hmm)


SAE Viscosity Grade T5 0W-40
Kinematic Viscosity (ASTM D445) @
40°C mm2/s 85.8
100°C mm2/s 15.0

Dyn. Index (ASTM D 5293)
@ -35°C mPa s 5800
Viscosity Index (ASTM D2270) 185
Total Base Number mgKOH/g (ASTM D2896) 9
Sulfated Ash % (ASTM D874) 1.2
Density @ 15°C kg/l (ASTM D 4052) 0.844
Flash Point (COC) °C (ASTM D92) 230
Pour Point °C (ASTM D97) -48

So, is that good?



Gannet,

As Catterham stated, this info does not include the HTHS value. Contacting Shell would be worthwhile to find out exactly what it is before choosing it.

Just to give you a practical example of HTHS, I will use a bunch of different Redline Oil examples:

RL 0W30, HTHS 3.2, Kin. Vis. @ 100C = 10.9
RL 5W30, HTHS 3.8, 10.6

RL 0W40, HTHS 4.0, 15.1
RL 5W40, HTHS 4.6, 15.1


So, to explain a bit... Using the 30 grade oils, the 0W30 has a higher viscosity at 100C than the 5W30 does, but the 5W30 has a considerably higher HTHS value. This means, that under high pressure and and high shear conditions at 150C, the 5W30 will actually be "thicker" than the 0W30, even though the 0W30 is more viscous under non-stressful (ambient) conditions at 100C.

The same applies for the 40 grade oils (the 0W40 and 5W40 both share the same kinematic viscosity, but you can see how the HTHS of the 5W40 is much higher than that of the 0W40). The higher HTHS will give you a greater film strength in the bearings at the expense of some crankability and cold flow in extreme cold temperatures.

Also, just for illustration purposes, let's compare Redline's 5W30 to their 0W40. The 0W40 is much more viscous at 100C under no pressure / load (10.6 cSt for the 5W30 vs. 15.1 cSt for the 0W40). However, the HTHS values are very close (3.8 vs. 4.0). This means that at 150C, under high pressures and high shear conditions (i.e. under load in a bearing), the two oils will act very similarly.

This means that with the Redline 5W30, you will get nearly the same film strength in the main bearings as the Redline 0W40, but the rest of the engine will enjoy a higher maximal flow of oil due to less pressure required to pump the 5W30.

The thought process in this example is applicable to all oils when you have all of the necessary information for them. So, make sure you consider HTHS in your search for an oil rather than just the grade of oil. A typical good conventional 5W30 has an HTHS of 2.9-3.2 cSt. Thus, simply switching to an xW30 Euro oil, xW30 diesel oil, or a robust HM oil that has a higher HTHS (say 3.6 for example) would give you that added film strength in your main bearings without actually requiring a significantly higher viscosity oil.

Hope that makes sense.

 

[CATERHAM]

il_Signor97 you're on the right track except HTHS vis is a measure of viscosity, a more accurate measure than kinematically.

The fact that it's taken at 150C throws a lot of people because it actually trumps the less accurate 100C k'vis spec. If you know the HTHS vis of an oil and you want to understand what's going on in an engine at operating temps it's best to simply forget about the kinematic 100C vis spec'.
Using your RL 5W-30 example, with it's HTHS vis of 3.8 cP it's for all intents and purposes a light 40wt oil and that's how it behaves even at cooler operating temps at least as low as 70C and of course all temps higher.

Another example of how HTHS vis' correlates with the operating viscosity in an engine more than the kinematic 100C vis' is fuel economy.
All things being equal, like base oil chemistry the add' pac', the oil with the lower HTHS vis' will have the best fuel economy regardless of what the oils 100C k'vis spec' is.

 

[il_signore97]

Originally Posted By: CATERHAM
il_Signor97 you're on the right track except HTHS vis is a measure of viscosity, a more accurate measure than kinematically.

The fact that it's taken at 150C throws a lot of people because it actually trumps the less accurate 100C k'vis spec. If you know the HTHS vis of an oil and you want to understand what's going on in an engine at operating temps it's best to simply forget about the kinematic 100C vis spec'.
Using your RL 5W-30 example, with it's HTHS vis of 3.8 cP it's for all intents and purposes a light 40wt oil and that's how it behaves even at cooler operating temps at least as low as 70C and of course all temps higher.

Another example of how HTHS vis' correlates with the operating viscosity in an engine more than the kinematic 100C vis' is fuel economy.
All things being equal, like base oil chemistry the add' pac', the oil with the lower HTHS vis' will have the best fuel economy regardless of what the oils 100C k'vis spec' is.





Agreed. And I believe I made a typo in my previous post that I cannot edit now. The "cSt" that I typed after the HTHS values should be "cP".

 

[Gannet167]

This makes me think that the grade of an oil is a somewhat outdated and maybe irrelevant method of measuring its properties. After all, when looking for a high shear strength, typically you look for a thicker oil. But if HTHS is a better measure of this then perhaps that's the better number to look for - perhaps giving the desired protection with a better flowing oil for cold start/fuel economy reasons.

So, expanding my search for a better oil beyond the Rotella 0w-40, what other oils come recommended with a good HTHS? I will ask Shell about their HTHS #'s.

 

[addyguy]

The question is, do you NEED a really high shear-strength oil?

Unless you are racing the heck out of your car, HT/HS is not an important number to focus on for a street oil.

From what I have learned here, engines only start having real problems if the HT/HS falls below 2.6 or 2.4......

I don't know if it is higher than Shell's but Petro-Canada Duron-E 0W-40 has a HT/HS of 4.04.

 

[il_signore97]

Originally Posted By: addyguy
The question is, do you NEED a really high shear-strength oil?

Unless you are racing the heck out of your car, HT/HS is not an important number to focus on for a street oil.

From what I have learned here, engines only start having real problems if the HT/HS falls below 2.6 or 2.4......

I don't know if it is higher than Shell's but Petro-Canada Duron-E 0W-40 has a HT/HS of 4.04.




Your point is valid, in that he may not "need" an oil with a high HTHS from a wear point of view. The bearings in his engine design may be protected just fine with a lower HTHS oil.

However, the point that others have made (specifically Catterham) is that the HTHS of an oil can also be viewed as an indicator of how "thick" the cushion of oil within the bearings will be, even at temperatures and shear rates lower than those encountered during the HTHS test itself.

Thus, the OP is looking for an oil that could provide a thicker film in his bearings. An oil with a higher HTHS will do that, regardless of whether he needs the added protection or not.

 

[il_signore97]

Originally Posted By: Gannet167
This makes me think that the grade of an oil is a somewhat outdated and maybe irrelevant method of measuring its properties. After all, when looking for a high shear strength, typically you look for a thicker oil. But if HTHS is a better measure of this then perhaps that's the better number to look for - perhaps giving the desired protection with a better flowing oil for cold start/fuel economy reasons.

So, expanding my search for a better oil beyond the Rotella 0w-40, what other oils come recommended with a good HTHS? I will ask Shell about their HTHS #'s.



The oil grading system is a bit cumbersome, but still applies. Traditionally, people always went to a thicker oil (i.e. up to a 40 grade from a 30 grade) whenever they wanted a thicker oil film. In reality, this choice was valid because thicker oils will *usually* have higher HTHS viscosities than thinner oils. I emphasize the word usually because in my previous Redline example, you can see that there are cases where high end synthetics defy this traditional logic.

So with modern oils, you may be able to get a much higher HTHS oil without moving up to a higher grade.

 

[Gannet167]

I am pretty certain I have a bottom end bearing problem. Nothing will prevent the car from eventually dying. But using a good oil may keep it alive a few more miles. I'm looking for a strong oil to help reduce the high wear numbers I'm getting. Certainly using a very poor oil is only going to make the wear problem worse.

Something inside the engine is shearing through oil and causing a lot of wear. What number should I be looking for if I want to reduce wear (likely caused because metal parts are shearing through the oil at smacking into each other)?

 

[Gannet167]

That Petro-Canada Duron 0w-40 looks amazing.

 

[CATERHAM]

Originally Posted By: Gannet167
This makes me think that the grade of an oil is a somewhat outdated and maybe irrelevant method of measuring its properties. After all, when looking for a high shear strength, typically you look for a thicker oil. But if HTHS is a better measure of this then perhaps that's the better number to look for - perhaps giving the desired protection with a better flowing oil for cold start/fuel economy reasons.

So, expanding my search for a better oil beyond the Rotella 0w-40, what other oils come recommended with a good HTHS? I will ask Shell about their HTHS #'s.


Congrat's you've got it and few people do get it!
HTHS vis is the more accurate measure of how thick the oil is at operating temperature and it trumps the less accurate 100C k'vis spec', PERIOD.

For cold temp' flow in our climate look a the 40C vis spec'. The lower the better.

As far as an oil's viscosity is concerned that's 99% of all you need to know.

 

[StevieC]

Caterham, then what is the best HTHS 5w20 out there? That should suffice my needs right?

RLI is it?

 

[il_signore97]

Originally Posted By: Gannet167
Something inside the engine is shearing through oil and causing a lot of wear. What number should I be looking for if I want to reduce wear (likely caused because metal parts are shearing through the oil at smacking into each other)?



We can all sit here and guess at what your problem might be, but if you really want to be pointed in the right direction, you can send an oil sample to Terry Dyson. Google Dyson Analysis. The price is admittedly steep, but he will give you the best advice as to what could be causing your high wear metals. Problems can range from actual physical bearing damage or wear, high abrasives in the oil from poor air filteration, fuel dilution causing oil breakdown and wear, etc, etc, etc.

 

[StevieC]

Agreed, no one will do a better UOA and analysis then Terry. He is very through, in-depth and is eager to please and will answer the million questions you have with scientific evidence and proof and with historical data.

Well worth the $$$ IMO. But make your own decision...

 

[Gannet167]

I'm going to go with PetroCanada Duron-E 0w-40. It's got great performance #'s and it's a little cheaper than the Rotella T5 (although I have to buy a case of 16 liters, but that's ok).

I called Shell and they say that HTHS #'s are "proprietary." I told them I don't want the secret formula, just the data that the competition is publishing. No luck.

 

[il_signore97]

Good choice. I believe forum member Overkill is using that in his Expedition.