Oil for Commodore LS1

[ElastoHydro]

Originally Posted By: Ducman

I note your comparison of critical engine clearances.
Note the minimum clearances.
I've done the same investigation myself in order to get to the bottom of the matter, and make sense of it my own mind.
Previously I also felt the thin oil requirement for LS series engines, may simply be an internet myth.
With reference to the factory clearance tolerances of the LS2 engines.
I flat out wouldn't like to be running any of the thicker oils in my engine, if I happen to draw the short straw if the clearances in my engine happen to be at the bottom of the tolerance range.
Only to potentially have insufficient oil flow, due to the oil being too thick.
Boundary lubrication is not my idea of an ideal scenario.


The clearance is still above the minimum oil film thickness needed to be hydrodynamic in those journal bearings. The question of thick vs. thin has more to do with the designer's use of the oil film thickness calculation of (viscosity x RPM) / BearingPressure. Lots of discussion on the Stribeck relationship formula for oil film bearing riding. For a bearing to lower the BearingPressure, they would be constructed wider. I wonder how the BMW S65 and GM LS1 V8's bearings compare in width, the wider one being able to use thinner oil.

 

[Ducman]

Originally Posted By: ElastoHydro
Originally Posted By: Ducman

I note your comparison of critical engine clearances.
Note the minimum clearances.
I've done the same investigation myself in order to get to the bottom of the matter, and make sense of it my own mind.
Previously I also felt the thin oil requirement for LS series engines, may simply be an internet myth.
With reference to the factory clearance tolerances of the LS2 engines.
I flat out wouldn't like to be running any of the thicker oils in my engine, if I happen to draw the short straw if the clearances in my engine happen to be at the bottom of the tolerance range.
Only to potentially have insufficient oil flow, due to the oil being too thick.
Boundary lubrication is not my idea of an ideal scenario.


The clearance is still above the minimum oil film thickness needed to be hydrodynamic in those journal bearings. The question of thick vs. thin has more to do with the designer's use of the oil film thickness calculation of (viscosity x RPM) / BearingPressure. Lots of discussion on the Stribeck relationship formula for oil film bearing riding. For a bearing to lower the BearingPressure, they would be constructed wider. I wonder how the BMW S65 and GM LS1 V8's bearings compare in width, the wider one being able to use thinner oil.



I agree.

I have also wondered about the width of the bearings and how well they work with the thinner oils.
Another part of the equation, is the diameter of the oil galleries and the oil pump's ability to keep feeding the oil in large enough quantities, despite the rate it's bleeding out of the bearings, to adequately lube all of the critical parts as required.
I think the 5w component of the grade is universally accepted as being a very good all round part of the equation.

But I think GM has done their homework and know very well what oil works in these modern LS series engines in all their applications.

So I'm happily sticking with the 10w-30 grade in my engine for all the reasons I've outlined in my earlier post.
It's important to be happy and content in our choices for the right reasons.

 

[A_Harman]

30 weight. 5w or 10w, with a slight tip of the hat to 10w out of respect for the warm environment down under. I'm currently running Castrol Syntec 0w30, which is a heavy 30, and the piston slap from the engine is louder than it was with a light 30 such as M1 or PU.

 

[Mr_Incredible]

OP, I did a quick check for Queensland and didn’t see any place where the Dec temps were above 35c (98f). That’s about summer temps here. If you are in a place that gets hotter, is it by very much?

You would do well with a 40w oil. I use M1 0w-30 in my ’98 Z28. I’ve used thin 30w, thick 30w, and even 40w, and the UOAs came back essentially the same. I wouldn’t worry too much about it unless there are differences in my ’98 LS1 and whatever it is you have. Our temps get up to 105f, but usually we have a few days over 100* and that’s it. The rest of the summer is in the 90’s. We had 98f yesterday.

Piston slap? Please… It goes away before I get 50 yards down the road. I don’t worry about it. Purely (audio) cosmetic, unless you have a super-slapper that sounds like there’s tiny dwarves inside the engine digging for gold.

 

[QldKev]

I should have put climate specific info on here. Winter is approx min 8c with a max 22c, with say 5 nights a year getting down to 5c. Winter lasts less than a month, before starting to warm back up a bit. Summer is nights 25c with days 33c and high humidity. 35c to 36c would be very hot, but once a year it may hit it.

So it seems a 40 would be better for the climate.

 

[ElastoHydro]

Originally Posted By: QldKev

I should have put climate specific info on here. Winter is approx min 8c with a max 22c, with say 5 nights a year getting down to 5c. Winter lasts less than a month, before starting to warm back up a bit. Summer is nights 25c with days 33c and high humidity. 35c to 36c would be very hot, but once a year it may hit it.

So it seems a 40 would be better for the climate.


Don't go any heavier oil viscosity than needed. You lower wear in the crank bearings the lower the viscosity, down to a point around 2.5 HTHS. Conclusion: Use a 30 oil in your application. Reference this Article Link look at Page 3 and notice that a good xw-30 synthetic oil will have a Vd HTHS of about 3, lots of room and less bearing wear than you'd get by going with a heavier 40 oil.

 

[ElastoHydro]

Originally Posted By: Ducman

So I'm happily sticking with the 10w-30 grade in my engine for all the reasons I've outlined in my earlier post.
It's important to be happy and content in our choices for the right reasons.


See my next earlier post, the tech paper. Your choice of a 30 should be perfect due to those charts.

 

[neo3]

Originally Posted By: ElastoHydro

Don't go any heavier oil viscosity than needed. You lower wear in the crank bearings the lower the viscosity, down to a point around 2.5 HTHS. Conclusion: Use a 30 oil in your application. Reference this Article Link look at Page 3 and notice that a good xw-30 synthetic oil will have a Vd HTHS of about 3, lots of room and less bearing wear than you'd get by going with a heavier 40 oil.


Thanks for referencing that interesting paper.
I looked at the graphs and the abstracts of the two papers that produced the graphs (didn't want to spend the $48 to download the entire papers). First, according to the caption of fig. 2a from the 89 paper, Vd is viscosity but it's not clear if it's the same as HTHS viscosity. The two graphs 3a and 3b from the 92 paper do show HTHS on the horizontal axis, but there are no data points over HTHS=3.0, and the wear data points are basically flat from 2.4 to 3.0, with big spikes (larger bearing wear) at the lower end around HTHS 2.2 to 2.4.

Also here's a quote from the abstract of the 92 paper:
Quote:
There were many instances of very high wear in cabs operated with the lowest viscosity oils but none in cabs with higher viscosity oils. Non-Newtonian oils appeared to provide slightly more protection than Newtonian oils of the same HTHS viscosity, and a higher quality adpack also appeared to provide benefits. However, these factors were secondary to the viscosity of the oil. HTHS viscosity was a better predictor of bearing wear performance than oil film thickness.

 

[Shannow]

Originally Posted By: ElastoHydro

Don't go any heavier oil viscosity than needed. You lower wear in the crank bearings the lower the viscosity, down to a point around 2.5 HTHS. Conclusion: Use a 30 oil in your application. Reference this Article Link look at Page 3 and notice that a good xw-30 synthetic oil will have a Vd HTHS of about 3, lots of room and less bearing wear than you'd get by going with a heavier 40 oil.


From the paper you quoted, there is more con-rod bearing wear the lower the HTHS...the tests are engine specific. You don't like bench tests, but will happily recommend tests on engine A across to engine B.

And as per the queted SAE paper, minimum oil film thickness should be the parameter by which a lubricant should be chosen, as at a vcertain minimum oil film thickness "catastrophic" failure occurs....i.e. it is concluded that MOFT in an operating engine is the optimum test for lubricant performance in a journal bearing.


You will never get "catastrophic" failure from a 40 weight, but get below the MOFT beyond which failure is certain and you will...and you can't measure MOFT, or how close to the margin you are.

 

[neo3]

Originally Posted By: Shannow

And as per the queted SAE paper, minimum oil film thickness should be the parameter by which a lubricant should be chosen, as at a vcertain minimum oil film thickness "catastrophic" failure occurs....i.e. it is concluded that MOFT in an operating engine is the optimum test for lubricant performance in a journal bearing.


lol I didn't catch that... the first paper says MOFT is the best measure and HTHS is deficient, the second paper says that HTHS is the best measure (see my quote above) and MOFT is deficient. So, they cancel each other out I guess.

 

[Garak]

Originally Posted By: QldKev
So it seems a 40 would be better for the climate.

Trust me, these and other GM familes of engines have done very, very well on basic, ILSAC type 30 grades for a long, long time. Buy by price and don't worry about trying anything exotic, be it an exotic brand or a strange grade.

 

[Ducman]

Originally Posted By: QldKev

I should have put climate specific info on here. Winter is approx min 8c with a max 22c, with say 5 nights a year getting down to 5c. Winter lasts less than a month, before starting to warm back up a bit. Summer is nights 25c with days 33c and high humidity. 35c to 36c would be very hot, but once a year it may hit it.

So it seems a 40 would be better for the climate.



It's probably way over kill on these engines.

Remember Mark Sfaife and Mobil did that drive around OZ in a 6.0l VZ ute on a single fill of Mobil 1 5w-30.
A well formulated 5w-30 grade, that's at the thick end of its viscosity spectrum will be plenty good enough all over OZ all year round.

As a guide.
I'm located in Brisbane, and I like to unnecessarily warm up my engine a bit(for good measure) for only a couple of minutes with the 10w-30 before I gently drive off in winter.
The viscosity of my oil at 40 C is 62.5 cSt and at 100 C it's 10.5 cSt, with a HTHSV of 3.2.

 

[ElastoHydro]

Originally Posted By: Shannow
....at a vcertain minimum oil film thickness "catastrophic" failure occurs....i.e. it is concluded that MOFT in an operating engine is the optimum test for lubricant performance in a journal bearing.


Wait.... do you have the rank of Captain? Is this you?

Of course a bearing kind of needs an oil film. Why not use a 60 weight, by your logic, more is better. The OP's engine is designed for a 30, so yes, I'll bet an oil film will form.

 

[dailydriver]

Originally Posted By: ElastoHydro
Originally Posted By: Shannow
....at a vcertain minimum oil film thickness "catastrophic" failure occurs....i.e. it is concluded that MOFT in an operating engine is the optimum test for lubricant performance in a journal bearing.


Wait.... do you have the rank of Captain? Is this you?

Of course a bearing kind of needs an oil film. Why not use a 60 weight, by your logic, more is better. The OP's engine is designed for a 30, so yes, I'll bet an oil film will form.


Shannow's in Oz, so they may not get those TV commercials there (?), and he may have NO idea that is "Captain Obvious" to us here in the states.

 

[Shannow]

It would help if our banned paper plane enthusiast come fleet manager quoted the whole of my post...but he didn't do that as farfetched either

 

[Garak]

Shannow, it's hard to type properly when one is using one's hands to manipulate sockpuppets.

 

[boundarylayer]

Originally Posted By: Shannow
From the paper you quoted, there is more con-rod bearing wear the lower the HTHS...the tests are engine specific. You don't like bench tests, but will happily recommend tests on engine A across to engine B.

And as per the queted SAE paper, minimum oil film thickness should be the parameter by which a lubricant should be chosen, as at a vcertain minimum oil film thickness "catastrophic" failure occurs....i.e. it is concluded that MOFT in an operating engine is the optimum test for lubricant performance in a journal bearing.


The Captain Obvious reference to shannow does hilariously apply here for people who have a sense of humor. I don't think anyone would ever argue that oil films are necessary. Actually, shannow is wrong, con-rod bearing wear trends upward with excessively thick oils, like diagram 2a & 2b shows clearly in the paper referenced above; see the upward slope. Its only when the HTHS gets down to excessive small levels does the oil film collapse and wear increase due to asperity collisions.

Originally Posted By: Garak
Shannow, it's hard to type properly when one is using one's hands to manipulate sockpuppets.
Originally Posted By: Shannow
It would help if our banned paper plane enthusiast come fleet manager quoted the whole of my post...but he didn't do that as farfetched either


Stay on subject. Nobody values your weird commments. Either post about relevant topics or get out.

 

[Shannow]

elastohydro made the statement that bearing wear woud lower with hTHS down to 2.5, and referenced a paper, which had nothing to do with the engine design, and I pointed it out...as farfetched, elastohydro was continually calling me on bench testing,and other deisgns not being appropriate to anyargument...he can't take one desing/test, and state that wear will reduce down to 2.5 in an LS1...simple and on topic.

chart 3b on that paper shows more con rod wear with lower viscosity, and the papers referenced state that measurement of oil film thickness is best used for wear prediction than HTHs...with was elastohydro's premeise.

Google the two referenced papers...it's not THAT hard.

Again...the paper references two other SAE papers, which do not conclude that wear in an LS1 will reduce down to 2.5HTHS, and the second paper's chart is interesting when looked at in light of OVERKILL's experience with Fords, and big end bearings suffering.

 

[Garak]

Originally Posted By: boundarylayer
Stay on subject. Nobody values your weird commments. Either post about relevant topics or get out.

The topic at hand is sockpuppets. It's been determined years ago that 30 grade oils are perfectly suitable in all climates in GM gassers, and plenty of other grades work. That problem has been solved decades ago, and there's little to add to it.

And speaking of Captain Obvious, we do, however, have different names saying the exact same things in the exact same voices. So, sockpuppetry is a valid concern, and an obvious one at that.