Best SAE30 weight oil?

[Shannow]

Originally Posted By: Gokhan
Also, straight grades take much longer to warm up (to thin to normal operating viscosity), increasing the warmup wear as well.


Nope, lower VI for the same operational viscosity will warm up quicker, as there's more internal shear.

As to proven to reduce wear...that's bearings at the limits of pumpability, which if you aren't experiencing (pumpability issues) with an SAE 30, you aren't getting (excesive bearing wear).

 

[bbhero]

Makes sense to me. What's the lowest temp you could run a SAE 30?? 5°C or 0°C ?? Possibly colder?? Though I very much doubt it could be done below 0°C.

 

[Gokhan]

There is a reference to an old SAE book that shows multigrade oils to show less bearing wear. It's called effects of viscosity or something like that. I have to dig it up.

By longer warmup I meant viscosity staying thicker for a longer time, not the actual warmup time, which shouldn't be much different.

 

[userfriendly]

I found 0C to be the lower limit for a quality SAE 40, and -10C for SAE 30. I ran Duron SAE 30 one winter (6.6 LML), but used the block heater more than usual.

 

[Shannow]

Originally Posted By: Gokhan
There is a reference to an old SAE book that shows multigrade oils to show less bearing wear. It's called effects of viscosity or something like that. I have to dig it up.


These ones ???...they tell a slightly different story...

Originally Posted By: Gokhan
By longer warmup I meant viscosity staying thicker for a longer time, not the actual warmup time, which shouldn't be much different.


It IS different enough that they are chasing the lower wasted power in the search for fuel economy.

How does the oil being thicker for longer increase wear ?

 

[Gokhan]

No, not that book. It could be the classic ASTM book on HTHSV by James A. Spearot. He had plots of wear rates for different HTHSV with and without VII.

Optimal oil flow won't be achieved with viscosity being too high.

 

[Shannow]

Originally Posted By: Gokhan
Optimal oil flow won't be achieved with viscosity being too high.


again, flow isn't lubrication...we've covered that ad nauseum...thicker oils need less flow to make up for side leakage, and have thicker MOFT...

 

[bbhero]

Thank you very much for answering my question userfriendly.

 

[Gokhan]

Originally Posted By: Shannow
Originally Posted By: Gokhan
Optimal oil flow won't be achieved with viscosity being too high.

again, flow isn't lubrication...we've covered that ad nauseum...thicker oils need less flow to make up for side leakage, and have thicker MOFT...

I'm not convinced by simple theoretical arguments that claim no oil is too thick or no viscosity is too high.

My counter example is the famous case of BMW bearings that were manufactured with too little clearances and as a result they were failing with 10W-60 but they were running fine with 0W-40.

 

[Shannow]

Originally Posted By: Gokhan
I'm not convinced by simple theoretical arguments that claim no oil is too thick or no viscosity is too high.


Firstly you might like to find a statement that I've made to that effect....you won't.

What I am countering is your continued statements that flow equals lubrication, as per AEHAAS and CATERHAM...it's plain wrong...I am not, and never have claimed your strawman.

 

[Gokhan]

Originally Posted By: Shannow
Originally Posted By: Gokhan
I'm not convinced by simple theoretical arguments that claim no oil is too thick or no viscosity is too high.

Firstly you might like to find a statement that I've made to that effect....you won't.

What I am countering is your continued statements that flow equals lubrication, as per AEHAAS and CATERHAM...it's plain wrong...I am not, and never have claimed your strawman.

I've never said flow equals lubrication. I'm well familiar with the fundamental curve of lubrication called the Stribeck curve and the different lubrication regimes it characterizes. I also doubt AEHaas or CATERHAM have ever said that either.

The problem is that there are two schools of thought here (I don't consider myself being in either) with opposing but good and often valid arguments. However, they refuse to understand the valid points of the other side.

 

[Shannow]

Originally Posted By: Gokhan
I've never said flow equals lubrication. I'm well familiar with the fundamental curve of lubrication called the Stribeck curve and the different lubrication regimes it characterizes. I also doubt AEHaas or CATERHAM have ever said that either.


You ALL say things like...

Originally Posted By: Gokhan
Optimal oil flow won't be achieved with viscosity being too high.


What does that mean if not that you are saying that lubrication is related to flow ?

 

[Gokhan]

Coming back to the topic of this thread, multigrade oils were found to result in less wear than single-grade oils. To me this is the end of story on whether I should use a single grade or multigrade in a car or truck engine:

'Engine wear tests were conducted, using two different engine designs, with single- and multigrade engine oils. In one engine there was a significant reduction in bearing wear when multigrade oils were used. For the other engine, there was evidence of less bearing wear when multigrade oils were used.

In both engines correlations were found among bearing wear, high-temperature, high-shear-rate viscosity, and oil elasticity.'

https://saemobilus.sae.org/content/872128

 

[Red91]

OK, your point has-been presented. Can you leave now before you get a good thread locked?

 

[Gokhan]

Not trying to start anything. I had studied it in the past and I thought it was worth posting.

 

[DoubleWasp]

Originally Posted By: Gokhan
Coming back to the topic of this thread, multigrade oils were found to result in less wear than single-grade oils. To me this is the end of story on whether I should use a single grade or multigrade in a car or truck engine:

'Engine wear tests were conducted, using two different engine designs, with single- and multigrade engine oils. In one engine there was a significant reduction in bearing wear when multigrade oils were used. For the other engine, there was evidence of less bearing wear when multigrade oils were used.

In both engines correlations were found among bearing wear, high-temperature, high-shear-rate viscosity, and oil elasticity.'

https://saemobilus.sae.org/content/872128


Possible things have changed with oil since 1987?

 

[Shannow]

Originally Posted By: DoubleWasp
Originally Posted By: Gokhan
Coming back to the topic of this thread, multigrade oils were found to result in less wear than single-grade oils. To me this is the end of story on whether I should use a single grade or multigrade in a car or truck engine:

'Engine wear tests were conducted, using two different engine designs, with single- and multigrade engine oils. In one engine there was a significant reduction in bearing wear when multigrade oils were used. For the other engine, there was evidence of less bearing wear when multigrade oils were used.

In both engines correlations were found among bearing wear, high-temperature, high-shear-rate viscosity, and oil elasticity.'

https://saemobilus.sae.org/content/872128


Possible things have changed with oil since 1987?


Cold start wear, below the useful range of monos, multis help with things like bearing wear.

Also, some of the polymers create a sort of cushioning tribofilm in high enough concentrations.

Bearing wear at operating temperature in real world applications is predominantly HTHS controlled... unless the type and quantity of the polymers to make the second point a player.

Most of the papers of the era recognise those facts...and they are still facts, but when a sentence or two wants to present a POV, they are facts left out.

 

[Red91]

Fair enough. Monogrades aren't stuck in the past though, as many modern SAE 30'S offer cold flow characteristics that really make them more like 15W-30 or 20W-30, without VII's. I imagine maybe the tiniest amount of synthetic base stock makes in into the mix. At least that seems to be a logical presumption.

 

[BrocLuno]

That's what I have discovered. Modern SAE 30's pour more easily than the old ones back in the day. Makes me suspect that you are right

 

[Gokhan]

It's also worth mentioning that the new SAE grades like 5W-16, 0W-12, 0W-8, etc. will actually often be single grades in construction, as in most cases no VII will be needed for such small spreads. Therefore, we are effectively having a return to single-grade oils in the future, albeit with thinner oils.

Note that they chose to use the multiples of 4 for the new SAE grades to eliminate consumer mixup.