10W-40

[smbrm]

Guys

1) The charts you are quoting are generic.
2) a &&W-20 can have a kinematic viscosity between 5.6 to 9.3 cast at 100C.
3) the oil you choose to use may not be appropriately represented by these charts.
4) these charts only reflect KINEMATIC viscosity. You cannot deduce DYNAMIC HTHS viscosity of a multigrade engine oil from a kinematic viscosity chart. That is why HTHS exists and why it is a different test.
5) If engine durability under extreme operating conditions is the concern, then an understanding of HTHS is more relevant to your concern than operating temperature kinematic viscosity.

I know it's fun to try and figure out the answer, but if someone would ask Subaru/Scion for more detail regarding the owners manual recommendations on this topic at least you would have a benchmark to compare what you think you can deduce against.

[bluesubie]

Originally Posted by smbrm

I know it's fun to try and figure out the answer, but if someone would ask Subaru/Scion for more detail regarding the owners manual recommendations on this topic at least you would have a benchmark to compare what you think you can deduce against.

IMO, they won't offer anything other than to follow what is stated in the manual. Too bad they allow thicker viscosities in certain conditions but do not define what those viscosities are (like the pre-2011 Subaru manuals did).

-Dennis
P.S. - Pretty soon we'll be posting, "Wow, this 0W-10 is thin. Can I use 0W-20 at the track?"

Shell pushes lubrication boundaries with fuel-saving 0W-10 synthetic motor oil

And

The SAE Engine Oil Viscosity Classification (EOVC) Task Force has been gathering data in consideration of extending SAE J300 to include engine oils with high temperature, high shear rate (HTHS) viscosity below the current minimum of 2.6 mPa∙s for the SAE 20 grade. The driving force for doing so is fuel economy, although it is widely recognized that hardware durability can suffer if HTHS viscosity is too low. Several Japanese OEMs have expressed interest in revising SAE J300 to allow official designation of an engine oil viscosity category with HTHS viscosity below 2.6 mPa∙s to enable the development of ultra low friction engines in the future. This paper summarizes the work of the SAE EOVC Low Viscosity Grade Working Group comprising members from OEMs, oil companies, additive companies and instrument manufacturers to explore adoption of one or more new viscosity grades. Past studies relating HTHS viscosity to engine wear will be reviewed, and an analysis of the rheological properties of commercial SAE xW-20 oils will be presented. New data will also be offered to demonstrate the feasibility of formulating engine lubricants to meet HTHS viscosities as low as 1.7 mPa∙s while meeting current low temperature oil starting viscosity and ILSAC volatility requirements. Finally, the paper will address the measurement precision of current HTHS methods on prototype low HTHS engine oils.

http://papers.sae.org/2010-01-2286/

Motul offers 0W-15 race oil now.

[smbrm]

You are probably right about Subaru, but even if they tell you, that you are on your own, at least you know that for sure! There is always a chance there is more info if they are pressed.

And, yes, Good find, that is how the process begins, to change the viscosity grading system. The 0W-10 has been mentioned before in a previous thread. Technology marches on!!

[ZDan]

Originally Posted by smbrm

1) The charts you are quoting are generic.

I gave a disclaimer, no idea the validity of the chart I posted, it's for illustrative purposes and conjecture

2) a &&W-20 can have a kinematic viscosity between 5.6 to 9.3 cast at 100C.
3) the oil you choose to use may not be appropriately represented by these charts.
4) these charts only reflect KINEMATIC viscosity. You cannot deduce DYNAMIC HTHS viscosity of a multigrade engine oil from a kinematic viscosity chart. That is why HTHS exists and why it is a different test.

If you have info, share it please! If not, the *general* assumption I would make is that a 5w30 or 10w40 will have a more appropriate HTHS at elevated temperatures.

5) If engine durability under extreme operating conditions is the concern, then an understanding of HTHS is more relevant to your concern than operating temperature kinematic viscosity.

But if HTHS values aren't available and I don't have a test lab, I *still* have to decide what oil to run.

I know it's fun to try and figure out the answer, but if someone would ask Subaru/Scion for more detail regarding the owners manual recommendations on this topic at least you would have a benchmark to compare what you think you can deduce against.

I wouldn't hold my breath waiting for a reply.

Me, if I was to be tracking a Toyobaru, particularly in warm weather, I'd just run a trusted 5w or 10w30 synthetic and not worry further until more info is available.

Not giving this as advice necessarily, but that's what I'd do...

[rice_classic]

Originally Posted by smbrm

2) a &&W-20 can have a kinematic viscosity between 5.6 to 9.3 cast at 100C.

That seems like too large a variance to categorized as a 0w-20.

What 0w-20 has a 5.6 cSt@100C?

[smbrm]

Originally Posted by rice_classic

That seems like too large a variance to categorized as a 0w-20.

What 0w-20 has a 5.6 cSt@100C?

You may wish to read the specs previously provided.


http://www.infineum.com/Documents/AP...ils%202010.pdf


Whether or not any are designed at the low end of the spec. is a different question.

The point was about making assumptions based on incomplete information or interpretation.

[smbrm]

Originally Posted by ZDan

I gave a disclaimer, no idea the validity of the chart I posted, it's for illustrative purposes and conjecture

If you have info, share it please! If not, the *general* assumption I would make is that a 5w30 or 10w40 will have a more appropriate HTHS at elevated temperatures.

But if HTHS values aren't available and I don't have a test lab, I *still* have to decide what oil to run.


I wouldn't hold my breath waiting for a reply.

Me, if I was to be tracking a Toyobaru, particularly in warm weather, I'd just run a trusted 5w or 10w30 synthetic and not worry further until more info is available.

Not giving this as advice necessarily, but that's what I'd do...

A) I was attempting to clarify/ confirm the relevance of the chart and your disclaimer.

B) I would agree that 5W-30 and 10W-40 would have higher HTHS since they should by the spec definition.

C) the question from the outset is how to decide what is thick enough? If your criteria is exclusively durability then thicker is better, until you reach a point where what is thick enough for on track becomes too thick for another consideration, eg. everyday use, low temperature requirements, more power, fuel consumption or other mechanical consideration that would make a choice too thick.

D) If you can't find or ask for or acquire HTHS characteristics for oils then perhaps you may wish to consider oils that do have that info. Reputable lubricant manufacturers have technical "helps" lines with folks that may be able to help you with info and product selection.

E) the "functional" difference between an HTHS of 2.6 & 2.7 is neither here nor there, while the difference between 2.7 & 3.3 or 3.5 can be more significant.

F) My contribution has been to attempt to direct the focus to asking the more appropriate questions which should lead you to a better answer. So over to you guys to ask the better questions.

[ZDan]

Originally Posted by smbrm

B) I would agree that 5W-30 and 10W-40 would have higher HTHS since they should by the spec definition.

My point: *if* oil temps run high at the track (and no one will know this unless they install a sensor and oil temp gauge), running 0W or 5W or 10W (if no exposure/usage at very low temps) 30 or 40 are a reasonable compromise with no appreciable (probably not measurable) downside.

I personally wouldn't track it with 0W20 in the crankcase with no knowledge of what oil temps would be.

As far as I'm concerned, the only appropriate question is "what is the oil temperature for your usage?", but not many are going to know the answer. So, if tracking, 30 or 40 is, to me, a reasonable approach.

[bluesubie]

Don't forget that the engine was designed with use of a 0W-20 in mind. I know that Crawford Performance runs Motul 300V 0W-40 (which is even thicker down to around -15F than 300V 5W-30), but it is a built engine that is far from stock.

As I posted above, you can plug in some 40C and 100C numbers here to get a better idea of kinematic viscosity at a given temp:
http://www.widman.biz/English/Calculators/Graph.html

Since these cars are new, people will need to experiment with how different kinematic and HTHS viscosities affect oil pressure and oil temp. The last thing that you want at the track is oil that is too thick, creating unnecessary drag and heat, but something not too thin to cause metal to metal contact (boundary lubrication).

-Dennis

[smbrm]

Originally Posted by bluesubie

Since these cars are new, people will need to experiment with how different kinematic and HTHS viscosities affect oil pressure and oil temp. The last thing that you want at the track is oil that is too thick, creating unnecessary drag and heat, but something not too thin to cause metal to metal contact (boundary lubrication).

-Dennis

I can't understate the wisdom in consulting a variety of the lubricant manufacturers in the process, as they should know the most about their specific products and tracking applications. Either that or you may get some interesting opinions regarding how accountable they might be for their product performance in tracking applications. Besides they get paid to answers your kind of questions!

[bluesubie]

Originally Posted by smbrm

I can't understate the wisdom in consulting a variety of the lubricant manufacturers in the process, as they should know the most about their specific products and tracking applications. Either that or you may get some interesting opinions regarding how accountable they might be for their product performance in tracking applications. Besides they get paid to answers your kind of questions!

Great point! In the past, I've had correspondence with Red Line, an East Coast Motul distributor, the Pennzoil Global Brand Manager and Mobil1 about specific recommendations for my application.

I think providing details are key in getting the best recommendation for the application (and not just an email asking what oil should I use in my FRS?).

-Dennis