Optimal kinematic viscosity for mimimal wear?

[saaber1]

Originally Posted By: JAG
Originally Posted By: CATERHAM
With all the talk on thick vs thin (i.e. 20 wt or lighter oil) I've always thought there must be a definitive scientific answer.

Here is some science: http://www.imeche.org/NR/rdonlyres/AF17C...yefficiency.pdf

JAG, thanks for posting that. That presentation is a wealth of information.

Just excellent!

I recommended taking a look if you haven't seen it.

And Jag if you have more of these, please post more if you got em' Much appreciated.

 

[JAG]

Originally Posted By: saaber1
And Jag if you have more of these, please post more if you got em' Much appreciated.

Sure thing. Here is another one by the same author, Ian Taylor. But this one is all text, instead of slides. http://physicsworld.com/cws/article/print/5020

I really enjoyed this one too, called, "Lubrication, Tribology & Motorsport": http://www.eng.auburn.edu/~jacksr7/SAE2002013355.pdf

A good bobistheoilguy thread is here: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1212235&fpart=1

I have not been posting my own thoughts lately in this and many other threads because I get too irritated by too many of the comments made. I believe there are people here who do understand the science, engineering, and chemistry relating to lubrication when it is presented so I do like to post links to such things for them.

 

[BuickGN]

Originally Posted By: ekpolk


You rely upon statements like this:
Quote:
Whether you want to admit it or not, a thicker oil reduces the chances and frequency of metal to metal contact period. I've seen it first hand many times from my own engines
, but with no specifics at all. So, show me an engine meant to use high-efficiency oils that has actually suffered from their use. Don't worry, I won't hold my breath. . .

Specifics? I've seen it with my own eyes. You've seen the evidence, you choose to ignore it. I'm not going to post over and over what has already been posted here. You choose to manipulate and twist the facts so enjoy your inferior oil.

 

[ekpolk]

Originally Posted By: BuickGN
Originally Posted By: ekpolk


You rely upon statements like this:
Quote:
Whether you want to admit it or not, a thicker oil reduces the chances and frequency of metal to metal contact period. I've seen it first hand many times from my own engines
, but with no specifics at all. So, show me an engine meant to use high-efficiency oils that has actually suffered from their use. Don't worry, I won't hold my breath. . .

Specifics? I've seen it with my own eyes. You've seen the evidence, you choose to ignore it. I'm not going to post over and over what has already been posted here. You choose to manipulate and twist the facts so enjoy your inferior oil.


And you choose to continue to believe that you can look at a couple isolated data points, and make broad, general conclusions from there. Not a valid approach at all. And speaking of ignoring facts, you continue to keep ignoring the MILLIONS of vehicles that are happily motoring along, many for over eight years, and showing no signs of a problem. Let's see, you've seen a couple of engines with problems (side note: it's not as if we have not seen wear related failures on thicker oils -- suggesting that there's more than vis at issue...), and against that, there are the millions of cars that are living long, uneventful lives on 20 wt oils. Yep, effectively protecting a car's engine until the car falls apart around it -- the very definition of inferiority in oils. . .

 

[Bryanccfshr]

Originally Posted By: JAG
Originally Posted By: saaber1
And Jag if you have more of these, please post more if you got em' Much appreciated.

Sure thing. Here is another one by the same author, Ian Taylor. But this one is all text, instead of slides. http://physicsworld.com/cws/article/print/5020

I really enjoyed this one too, called, "Lubrication, Tribology & Motorsport": http://www.eng.auburn.edu/~jacksr7/SAE2002013355.pdf

A good bobistheoilguy thread is here: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1212235&fpart=1



That was one of the most intense learning threads I have ever participated in.

 

[BuickGN]

Originally Posted By: ekpolk
Originally Posted By: BuickGN
Originally Posted By: ekpolk


You rely upon statements like this:
Quote:
Whether you want to admit it or not, a thicker oil reduces the chances and frequency of metal to metal contact period. I've seen it first hand many times from my own engines
, but with no specifics at all. So, show me an engine meant to use high-efficiency oils that has actually suffered from their use. Don't worry, I won't hold my breath. . .

Specifics? I've seen it with my own eyes. You've seen the evidence, you choose to ignore it. I'm not going to post over and over what has already been posted here. You choose to manipulate and twist the facts so enjoy your inferior oil.


And you choose to continue to believe that you can look at a couple isolated data points, and make broad, general conclusions from there. Not a valid approach at all. And speaking of ignoring facts, you continue to keep ignoring the MILLIONS of vehicles that are happily motoring along, many for over eight years, and showing no signs of a problem. Let's see, you've seen a couple of engines with problems (side note: it's not as if we have not seen wear related failures on thicker oils -- suggesting that there's more than vis at issue...), and against that, there are the millions of cars that are living long, uneventful lives on 20 wt oils. Yep, effectively protecting a car's engine until the car falls apart around it -- the very definition of inferiority in oils. . .

I'm tired of going in circles and restating things I've stated a hundred times already.

The "millions of vehicles happily motoring along" is irrelevent. We're talking the oil that is going to give the least amount of wear, not something that will last 200,000 miles. Two totally separate things. We've literally filled the crankcase with water in my friend's '81 Subaru and it ran fine for the week before we took it to the junkyard. Should I start advocating water as an ICE lubricant? It didn't fail so it must be the best choice for the lowest wear.

 

[ekpolk]

Originally Posted By: BuickGN
. . .

I'm tired of going in circles and restating things I've stated a hundred times already.
And you think I'm any less tired?

Originally Posted By: BuickGN
The "millions of vehicles happily motoring along" is irrelevent. We're talking the oil that is going to give the least amount of wear, not something that will last 200,000 miles. Two totally separate things. We've literally filled the crankcase with water in my friend's '81 Subaru and it ran fine for the week before we took it to the junkyard. Should I start advocating water as an ICE lubricant? It didn't fail so it must be the best choice for the lowest wear.

If "irrelevant" means "evidence I don't want to consider," then sure... But it's not. From where do you assume a life limit of 200k miles? If you apply just the roughest of averages, in the population of cars fed 20s since the inception of the 20 wt era, there will be many with less than 200k miles, and many with more.

As I've said many times, particularly given the prevalence of the internet, if 20s were as generally "inferior" as you want to believe, there would by now be a massive scandal underway that would make the little sludge skirmishes look trivial.

And ONCE AGAIN (you do never address this...), what is "inferior"? Any given 20 might be terribly unsuitable for a 60s muscle car with worn bearings and flat tappets, but ideal, and in fact, best for a modern new car. By contrast an SAE-60 oil might be fine for that muscle car, but would be awful for the a new Honda, Toyota, or Ford. Does either oil, in and of itself, possess some trait that makes it "superior" or "inferior"? Since you won't answer this, I will: NO, they don't. They're only "good" "bad" "thick" or "thin" in the context of where they're used.

And really now, resorting to the water example is just a silly ad absurdum argument. I wouldn't feed any of my cars' crankcases water any more than I'd flood them with super-high vis gear lube. The destruction in both cases would probably happen about as fast, and would in both cases be TOTALLY MEANINGLESS to the issue at hand.

 

[ekpolk]

I should also have added that I find it interesting that we are willing to draw many conclusions from our collection of UOAs. But when it comes to the damaging wear that is supposedly the price of using a 20 wt oil, all the evidence of such wear just happens to be that which just happens to be totally invisible to UOA, AND is completely invisible in the filter elements too. . .

 

[BuickGN]

Originally Posted By: ekpolk
I should also have added that I find it interesting that we are willing to draw many conclusions from our collection of UOAs. But when it comes to the damaging wear that is supposedly the price of using a 20 wt oil, all the evidence of such wear just happens to be that which just happens to be totally invisible to UOA, AND is completely invisible in the filter elements too. . .


Honestly, if the UOA came out in favor of the heavy oil I would not praise the oil. If it came out with tons of wear with a light oil, I would not condemn the light oil. I have that little faith in UOAs for measuring wear. I don't visit the UOA section anymore because I run my top notch synthetic for only 5,000 miles and I don't look at wear.

 

[Ben99GT]

The optimal kinematic viscosity is clearly

 

[CATERHAM]

Ben99GT, I appreciate the Canadian content (Mike Myers)!

 

[Rickey]

Oh boy! another thick VS thin "discussion"
May I join in please?


"If you drive a BMW M series car, then 10w-40 or 20w-50 is a dangerously "thin" oil. If you drive a Honda Accord or Toyota Camry, then 30, 40, and 50 wt oils are thick beyond optimal. And your reasoning about "thin" oils being used successfully because they contain EP/AW additives also does not fly. By this reasoning, you would need no such additives in your "thick" oils. But of course, they are most surely there."

OK mental exercise time:

Given new oil, a long steep mountain climb, a modern high performance V6 and a mild climate which of the following would you prefer:
A. Straight 5W oil with no additives.
B. Straight 50W oil with no additives.

Some folks may realize the need for mental floss after this.

"You also can not generalize that "thicker" oils (whatever those are) do a "better" job separating moving parts than thin oils under "pressure conditions." Oil, like all liquids, is a non-compressible fluid. If a car is designed for, and in proper condition so that it keeps the right amount of oil, in the right place (bearings), and at the right pressure, a "thin" oil will keep parts separated as well as a "thick" one. Obviously, it gets much more complicated than this in the real world. Many factors all come together to determine whether a particular oil will work in a given application. Viscosity is just one of those."

OK sir oil is non compressible,,,granted and agreed.
Please take in to account that journal bearings have side leakage and the rate of leakage is among other things dependent of an oil's viscosity.
So at a given temperature and load a journal bearing will have less operating clearance with an oil of lesser viscosity.

WHERE ARE THE ENGINEERS ON THIS BOARD ??????

 

[Rickey]

Paging Dr Haas

There has been another outbreak of "thickheadness"
Ward "GF4" the patients have taken the floor.
The outbreak is at present uncontained and spreading rapidly.
Please respond "stat"

 

[Sayjac]

Originally Posted By: ekpolk
Careful Pete, that's all you have -- theory and guesses. You keep preaching the "evils" of "thin" oils, while willfully blinding yourself to the clearest FACT of all -- that millions, yes millions of motor vehicles have been running quite happily, with no damage, for almost TEN FREAKIN' YEARS on these "evil, thin" oils. And they're just NOT having a problem. So your claim that,

Among other things, UOA, even inexpensive ones, show values for wear metals. OF COURSE, they are not conclusive, and all-revealing, but I do find it funny how members of the thick crowd run from them, declaring them "pointless" when again -- ooops -- they absolutely do NOT support your theories about terrible thin oils.

You rely upon statements like this:
Quote:
Whether you want to admit it or not, a thicker oil reduces the chances and frequency of metal to metal contact period. I've seen it first hand many times from my own engines
, but with no specifics at all. So, show me an engine meant to use high-efficiency oils that has actually suffered from their use. Don't worry, I won't hold my breath. . .

Well said. The most the thicker is better crew can come up with is some anecdotal tidbit, or a picture of some cam lobe, and say that proves their point.

But, all the stellar UOA's and the millions of miles with no empirical evidence of engine related failures due to the use of Xw20 weight oils where it's recommended, mean nothing.

And now the latest argument is you have to have torn down/rebuilt an engine to prove or speak authoritatively that 20 weight oils are not causing premature wear and engine failure. Just coincidentally, those folks, are the same thicker is better folks.

You see, that way you can ignore the all the stellar UOA's, the lack of empirical evidence to support your case, and the findings, writings and work of Dr. Haas on Xw20 and lighter weight oils.
Rather than spin, I too am waiting for some real evidence.

 

[Rickey]

I'm waiting for more engineers to show up and put a stop to the absurdity that is being propagated herein.

If you folks don't mind I'll quote myself and wait for someone to prove otherwise.

"OK sir oil is non compressible,,,granted and agreed.
Please take in to account that journal bearings have side leakage and the rate of leakage is among other things dependent of an oil's viscosity.
So at a given temperature and load a journal bearing will have less operating clearance with an oil of lesser viscosity."

There..... take a stab at that FACT.

 

[ravenchris]

Could be the increased rate of replenishment/flow due to lower viscosity neutralizes 'side leakage' effects.

 

[CATERHAM]

Rickey, what "oil of lessor viscosity" are you referring to?
Give us a kinematic number?

 

[Gary Allan]

Quote:
I don't think over the road trucks are operated at near maximum loads. The good drivers even when going up hills gear for minimum load on the engine otherwise the turbos will get too hot.


Would you buy a tri-axle dump only to put 5yrds of dirt in it and tool around the countryside? Would you buy a Class 8 rig and only load it to 20k. Would you waste the money. How about a bulldozer or a loader ..and only use them to 10% capacity?

No, you wouldn't. We drive cars and ..by gosh ..even pickup trucks way below their sensible limits.

Please ..(sigh) ..oh, never mind.

 

[OVERKILL]

Originally Posted By: sayjac
Well said. The most the thicker is better crew can come up with is some anecdotal tidbit, or a picture of some cam lobe, and say that proves their point.


I don't believe one has to look far to find that high-performance cars are almost all spec'd for a heavier grade of oil. Even when they share the same engine family with a lower-performance counterpart.

Ford spec'ing 5w20 for the Mustang GT, but 5w50 for the GT500 comes to mind.

Quote:
But, all the stellar UOA's and the millions of miles with no empirical evidence of engine related failures due to the use of Xw20 weight oils where it's recommended, mean nothing.

I don't recall anybody saying 5w20/0w20 was going to cause catastrophic engine failure. I believe the only argument here is that it provides less protection than a heavier oil.


Quote:
And now the latest argument is you have to have torn down/rebuilt an engine to prove or speak authoritatively that 20 weight oils are not causing premature wear and engine failure.


To provide any SOLID evidence that a heavier or lighter oil in a given application provides more or less wear DOES require tear-down testing.

Quote:
Just coincidentally, those folks, are the same thicker is better folks.

We are? I run 5w20 in both of my parent's vehicles......

Quote:
You see, that way you can ignore the all the stellar UOA's, the lack of empirical evidence to support your case, and the findings, writings and work of Dr. Haas on Xw20 and lighter weight oils.
Rather than spin, I too am waiting for some real evidence.

So, let me get this straight, we have two sources:

Doug Hillary, who is a Tribologist with decades of experience including fleet testing for a number of the major oil companies covering millions of Km, including performing routine UOA's on his fleets of vehicles, numerous recognized lubrication-related publications (one of which I own a copy of) and tear-down testing writes a paper on the value and mis-use of UOA's and posts it on this board.

Dr. Haas, who is a plastic surgeon, writes a paper on the theory of lubrication and the virtues of light oils, backing his information with UOA's in a couple of high performance cars that he owns.


And we are supposed to ignore the former and worship the latter because it supports the mantra that the thin-worshipping crowd preaches?

That makes sense.

How about just running an oil appropriate for the vehicle and its intended use that coincides with the recommendations of the manufacturer?

Oh wait, that's what Doug says, so it must not be correct..........

 

[Gary Allan]

OVERKILL ..can you show me one study that Doug has done on a Ford Escort with a low compression 1.9 engine living a normal life? Honda Civic? Geo Metro? Prius?

Every instance that I can recall, Doug has been on the leading edge of high performance R&D and HEAVY DUTY R&D.

When have you heard him comment on something that didn't spec AT LEAST a 40 grade from the OEM?

This is not at all meant to discount anything Doug says ..since I'm absolutely sure that it's GOLD ..but there's is a whole lot I've never seen him say (I can't hear him, but I can imagine it) ..since ..to tell you the truth, it's of no interest to him. I've never heard him comment on the mundane. That's just about our entire existence for most of us.