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#2194802 - 03/09/11 10:22 PM Flashpoint >n by grade. What does it mean?
jorton Offline


Registered: 07/04/03
Posts: 2698
Loc: San Antonio, TX
In blackstone reports, why do different grade oils have different flashpoint >numbers?

05w-20 = flashpoint >355
00w-30 = flashpoint >375
05w-30 = flashpoint >365
10w-30 = flashpoint >360
00w-40 = flashpoint >365
05w-40 = flashpoint >375
15w-40 = flashpoint >385
05w-50 = flashpoint >400

Can pistons ever get hotter than 355f? 400f?
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#2194824 - 03/09/11 10:45 PM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
2003f7 Offline


Registered: 02/14/09
Posts: 321
Loc: Kewaunee WI
Piston temps can reach 1200* f or more.
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#2194881 - 03/10/11 12:11 AM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
dtt004 Offline


Registered: 08/13/10
Posts: 314
Loc: Orange County, CA
Hi.

Ok to the above poster, flash point is usually measured in degrees C. 400 degrees C = 752 degrees F. By the way, I have never seen a car's pistons reach 1200 F. No offense, but that is theoretically impossible given the limits of the aluminum alloy used for pistons nowadays. The piston would simply melt. I do not know of any pistons that can withstand 1200 degrees F. The maximum threshold before failure is usually 700 K, which is about 426 degrees C.

A simple way to think of flashpoint is the point at which is vaporizes from a liquid into an ignitable gaseous phase mixture.

The number goes up with increasing oil viscosity because viscosity is directly proportional to the strength of the bonds in the carbon molecules inside the oil. This is why a higher viscosity oil will always provide greater protection by permitting an oil film to adhere to the lubricated parts at higher temperatures. Additives have an effect, but not as significant as the base stock itself.

That's why I believe the science behind these molecules rather than the marketing that is done; when a manufacturer says a lower viscosity oil will provide protection, what they are really saying is "it will provide enough protection for its intended use." And for the most part, people will never notice the difference. But from a science/engineering perspective all factors must be taken into account. Higher viscosity oils simply provide better film strength/adherence at higher temperatures. Those are simply laws of physics, thermodynamics, and fluid mechanics.
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#2194904 - 03/10/11 12:49 AM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
Brons2 Offline


Registered: 09/16/03
Posts: 2484
Loc: Austin, Texas
This should go in the "Oil Analysis - General Questions" forum.
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#2196266 - 03/11/11 05:59 AM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
jorton Offline


Registered: 07/04/03
Posts: 2698
Loc: San Antonio, TX
Originally Posted By: jorton
In blackstone reports, why do different grade oils have different flashpoint >numbers?

05w-20 = flashpoint >355
00w-30 = flashpoint >375
05w-30 = flashpoint >365
10w-30 = flashpoint >360
00w-40 = flashpoint >375
05w-40 = flashpoint >375
15w-40 = flashpoint >385
05w-50 = flashpoint >400

Can pistons ever get hotter than 355f? 400f?



Flashpoint temps are centigrade. Changed 0w-40 from 365 to 375.
_________________________
"If everything seems under control, you're just not going fast enough."
- Mario Andretti



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#2196383 - 03/11/11 09:00 AM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
INDYMAC Offline


Registered: 07/15/06
Posts: 2324
Loc: Magnolia, TX
Flashpoints can be listed as C or F. The flashpoints that are mentioned above are in F.
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#2197382 - 03/12/11 07:32 AM Re: Flashpoint >n by grade. What does it mean? [Re: jorton]
jorton Offline


Registered: 07/04/03
Posts: 2698
Loc: San Antonio, TX
Originally Posted By: jorton
Originally Posted By: jorton
In blackstone reports, why do different grade oils have different flashpoint >numbers?

05w-20 = flashpoint >355
00w-30 = flashpoint >375
05w-30 = flashpoint >365
10w-30 = flashpoint >375
00w-40 = flashpoint >375
05w-40 = flashpoint >375
15w-40 = flashpoint >385
05w-50 = flashpoint >400

Can pistons ever get hotter than 355f? 400f?



Flashpoint temps are centigrade. Changed 0w-40 from 365 to 375.


Now I don't know if synthetic is the same flashpoint as dino in the same grade.

Changed 10w-30 from 360 to 375.
_________________________
"If everything seems under control, you're just not going fast enough."
- Mario Andretti



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