I am tired of everybody saying 20 wt oils exist only for gas mileage

[1sttruck]

We have over 185k on one Taurus, it still runs well, but it seems to have a funny oil consumption pattern. We live on a hill and when driving up and down the hill several times a day we can go thru a quart of oil about every 500 miles, but on longer trips oil consumption can be half or less. I've been using a 10w30 dino and 5w40 synthetic blend for the last several oil changes, and with Mobil 1 T&S dropping to $4 a quart I'm on the verge of using just that. I'll keep track of oil consumption when I change to just T&S, and then try a 5w20 in the next change for comparison.

I also noticed that the emissions looked a bit better when I had it tested recently, where it seemed that the heavier oil blend may have helped compared to the 5w30 dino and 5w30 synthetic blend that I use to use.

 

[1911]

quote:

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Originally posted by MolaKule:
I would like to see actual in situ (inside engine) film thickness measurements made with various oils to see their actual thicknesses under idle and WOT when hot and cold.

This could be used to correlate data with the results of ASTM tests for high temperature high shear measurements.

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In large gas turbines, we actually can measure the film thicknesses with Bently Nevada proximity probes which measure distance from the probes to the shaft down to ridiculously low units. They are sensitive enough that they are used for vibration monitoring where the shaft may deflect a very infinitesimal amount.

We also must remember that the film thickness is very dependent on the pressure-viscosity coefficient (alpha coefficient) of the lubricant and PAO based ones are deficient in this area.

I am the 1911............and my slide rails are best lubed with 15W-40!!!

 

[MolaKule]

I would like to see actual in situ (inside engine) film thickness measurements made with various oils to see their actual thicknesses under idle and WOT when hot and cold.

This could be used to correlate data with the results of ASTM tests for high temperature high shear measurements.

 

[427Z06]

quote:

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Originally posted by 1911:
I am the 1911............and my slide rails are best lubed with 15W-40!!!

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My 1911 combat built .45 is a nice piece. But My Glock 20 is...ohhhh...so much better.

 

[427Z06]

quote:

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Originally posted by MolaKule:
I would like to see actual in situ (inside engine) film thickness measurements made with various oils to see their actual thicknesses under idle and WOT when hot and cold.

This could be used to correlate data with the results of ASTM tests for high temperature high shear measurements.

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I would imagine that you would have to run this test over a variety of engines to get any meaningful results.

Sometimes things ARE more complicated than they seem:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=010584

 

[mechtech]

1911 - Will you please give a layman's explanation of why the PAO are weak in the high pressure department?
thanks - John

 

[bulwnkl]

quote:

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Originally posted by 427Z06:
My 1911 combat built .45 is a nice piece. But My Glock 20 is...ohhhh...so much better.

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My 1911 is a nice piece, too. My brother's Glock, however, is merely a piece.

 

[1911]

quote:

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Originally posted by mechtech:
1911 - Will you please give a layman's explanation of why the PAO are weak in the high pressure department?
thanks - John

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HI John,

God knows I'm no physical chemist so I could not even begin to explain why the alpha coefficient is lower for PAO basestocks versus paraffinic oils and various esters...but trust me, it is lower indeed.

The pressure viscosity coefficient determines the amount of viscosity rise a lubricant undergoes when under pressure. PAO lubes do not undergo as dramatic an increase in viscosity with pressure. For some reason, nobody on this site has bothered to mention that lubricant viscosities typically go up between 100 and 1,000,000 times in the load zone of a bearing due to the massive pressure that can be applied. In a roller element bearing this can be up to 10,000,000 times. Also, lubricants are not really incompressible fluids either with densities growing about 20% when the pressure rises to 1000 Newtons/mm squared.

The significance of this is that film thicknesses are considered to be proportional to the alpha coefficient raised to an exponential power. Powers of around 0.6 are typically applied for elastohydrodynamic conditions like you would have with a highly loaded roller element bearing. The difference in the alpha coefficient between PAOs and mineral based lubes decreases as the temeprature rises.

Thanks,
1911

 

[JohnBrowning]

1911 and 427Z06, My Ruger Super RedHawk is just a dream! It is built like a hammer and is a hand loaders dream!! It is not picky about ammo,lube, weather etc.... It functions great strong side or weak and has no saftey!! It has a great single action pull and a nice double action as well! Not as nice a Molakules S&W but great just the same!

I know most people do not consider it a carry piece and I do not use it for carry but I have done it before. Luckily being built like a 1940's and 1950's lumber jack has it's advantages!

 

[427Z06]

I agree John, the Ruger Super RedHawk is one stout piece.

 

[427Z06]

quote:

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Originally posted by 1911:
Also, lubricants are not really incompressible fluids either with densities growing about 20% when the pressure rises to 1000 Newtons/mm squared.

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Since a Pascal = 1,000,000 Newtons/millimeter squared

And a Pascal = .000145 Pounds/inch squared

Aren't you talking the equivalent of the pressure wave created by a flea breaking wind at a 10 foot radius?

[ April 29, 2005, 03:12 AM: Message edited by: 427Z06 ]

 

[mechtech]

Maybe he meant kilopascal,the more usual term.

 

[1911]

quote:

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Originally posted by 427Z06:

quote:

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Originally posted by 1911:
Also, lubricants are not really incompressible fluids either with densities growing about 20% when the pressure rises to 1000 Newtons/mm squared.

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Since a Pascal = 1,000,000 Newtons/millimeter squared

And a Pascal = .000145 Pounds/inch squared

Aren't you talking the equivalent of the pressure wave created by a flea breaking wind at a 10 foot radius?

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Hey 10mm Auto Man (great gun),

You've got a math error in there. See below:

1 pascal =1 newton/meter squared.

Now 1 mm squared = one millionth of a meter squared so 1 Newton/millimeter squared equals the same force (1 Newton) applied over one million the area which is raises the nominal pressure one million times so :

1 Newton/milillimeter squared = 1 million Pascals or 1 MegaPascal.

Therefore 1000 Newtons per mm squared = 1000 Megapascals or 1 gigapascal or 10 raised to the 9th pascals.

A pascal equals one millionth of a newton per millimeter squared (which equals one newton/meter squared), not 1,000,000 newtons per millimeter quared as you said.

Thanks,
1911

 

[jtantare]

Why is 5w20/0w20 only sold and recomended in north America?

 

[JohnnyO]

quote:

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Originally posted by jtantare:
Why is 5w20/0w20 only sold and recomended in north America?

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Because we're the only place that mandates an fleet average minimum gas mileage. Other countries let high fuel taxes be the incentive.

 

[TallPaul]

quote:

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Originally posted by JohnnyO:

quote:

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Originally posted by jtantare:
Why is 5w20/0w20 only sold and recomended in north America?

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Because we're the only place that mandates an fleet average minimum gas mileage. Other countries let high fuel taxes be the incentive.

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True. And if the 5w20 was really any better than thicker oils, you would think it would be used in other countries. Also, if the fuel economy benefits were more than negligible for the individual user, they would have incentive to use it in Europe to offset the high taxes. Conclusion: 5w20 ain't worth much to me or you.

 

[427Z06]

quote:

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Originally posted by 1911:
You've got a math error in there.

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Oops.

(145,038 PSI)

Note to self: Don't attempt to do even simple math at 2 a.m. after imbibing a 6-pack-plus.

Anyway, even if we consider tribological theories and fine laboratory measurements, it doesn't discount the fact that when engines are run with spec-ed oil on a dyno for 300 hours at WOT and full load, the wear differences between base-stocks in fully formulated oils, are for all practical purposes, negligible.

 

[moribundman]

quote:

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Why is 5w20/0w20 only sold and recomended in north America?

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That's not correct. Even my 1989 German VW manual says 5W-20 can be used (although only for temps below 10 degree F). Honda recommends 0W-20 (not for the V-Tech) for best fuel efficiency in Japan, while they also recommend thicker oils.

PS: Am I the only one who enjoys 427Z06 and 1911 checking each other's math and facts?

 

[dbf]

Topic: I am tired of everybody saying 20 wt oils exist only for gas mileage ......How about we all get over it?

 

[427Z06]

quote:

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Originally posted by dbf:
How about we all get over it?

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Nope. We're going to beat on this dead horse until it emerges in China. Or would that be Australia? Anyone have a globe handy?