Does the 5+ Pi viscosity imply that the oil has precurved melecules so they will fit the journal bearings better?
It's too late to try and make any sense out of e+1
What Is the Perfect Oil Viscosity?
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It's too late to try and make any sense out of e+1
XS650, how did I know that you'd be the one to catch the little mathematical signatures.
5cS may be considered to be the amount we "thin is better" people like. 8cS may be the middle ground, the starting point for oil testing viscosities. 10cS or more may be where the "thick is better" people live.
These values are all well below the average thickness of oils at start-up, several hundred if not thousand centiStokes thicker.
This is why I say that one should pick the operating oil viscosity your application requires then use the oil with the highest viscosity index, the lowest 0W viscosity and lowest pour point characteristics.
If you are worried about thinning with use, use a synthetic oil. Since current mineral oils thin less with use as compared to older oils many feel mineral oils are safe. But they are inferior to the synthetic at start-up.
In any case start-up is an important area of automotive operation, even at 75 F. This area is most often ignored. It should be the area we discuss most for light duty engine operation.
aehaas
PS I caught the Pi as well and had to laugh!
These values are all well below the average thickness of oils at start-up, several hundred if not thousand centiStokes thicker.
This is why I say that one should pick the operating oil viscosity your application requires then use the oil with the highest viscosity index, the lowest 0W viscosity and lowest pour point characteristics.
If you are worried about thinning with use, use a synthetic oil. Since current mineral oils thin less with use as compared to older oils many feel mineral oils are safe. But they are inferior to the synthetic at start-up.
In any case start-up is an important area of automotive operation, even at 75 F. This area is most often ignored. It should be the area we discuss most for light duty engine operation.
aehaas
PS I caught the Pi as well and had to laugh!
In theory, yes, but then you have to deal with reality. If bearing clearances and/or oil pump volume allowed the use of 8 cSt @100C, you still have to deal with the HTHS issue as you need a certain minimum MOFT, especially if you're going to run the engine hard. Even with synthetics.
Further, most engines will tolerate viscosities of several hundred cSt. The relationship between adequate oil flow at startup and viscosities at startup isn't linear, and at least half the startup wear is due to the engine just being cold.
Finally building an oil with highest viscosity index, the lowest 0W viscosity and lowest pour point characteristics will lead to compromises in other areas unless you can find an oil blender who is willing to attempt to market a "no holds barred" combination of the very best basestocks and additives. I'm guessing that for a small company we're talking $20/qt oil then. The big boys won't do it since the market is to small and the margin is to thin.
Typo? the e decimal should go:
.718281828459045235360 , no?
So does e^(pi*i)+1=0 describe the perfect oil viscosity?
e = 2.71828182845904523536028747135266249775724709369995... the best I can tell. So...I guess it's a typo.
Shsssh, don't tell. Most Physicist and Engineers only use three significant figures.
Shsssh, don't tell. Most Physicist and Engineers only use three significant figures.
"The Perfect Viscosity" has nothing to do with oil. It has everything to do with the design of the engine. What might be "Perfect" for one engine will be totally unsuitable for another...If the engine lasts 5000 hours or more, then the viscosity and everything else must have been perfect....
An oil that has a viscosity of 3.5 cst at all temperatures and under all loads would be pretty sweet!
For most modern engines, I'd say an SAE 0w-30 is going to give you the best combination of protection and engine performance, including fuel efficiency. I haven't seen any issues in the ten years I've been using 0w-30, even in very hot climates. For an ultra high performance, European motor or a high mileage, worn engine, you could bump that up to 5w-40. I rarely see a gas engine that requires anything thicker than a 5w-40 for street use. Even air-cooled, Porsche 911 engines do fine with a 5w-40 grade.
Quite honestly, I don't understand people running 15w-40 oils in 5w-30 or even 5w-20 applications. All it does is hurt performance, cold starting and fuel efficiency. My thinking tends to run exactly the opposite way, ie run a synthetic that is one SAE grade LIGHTER than what's recommended for a petroleum oil in the specific application.
TS
Quite honestly, I don't understand people running 15w-40 oils in 5w-30 or even 5w-20 applications. All it does is hurt performance, cold starting and fuel efficiency. My thinking tends to run exactly the opposite way, ie run a synthetic that is one SAE grade LIGHTER than what's recommended for a petroleum oil in the specific application.
TS
Piston slappers, like my Subaru's engine, need thick oil cushioning while the pistons warm up.
I've been driving a while with 5w30 in my engine again, after draining the Redline 5w20, and the engine has much more low-end torque than with 5w20.
There's a small hill that I have to climb, and with 5w30, I can make it without pressing on the gas pedal hard enough to cause the torque converter clutch to unlock. With 5w20 in the engine, I almost always had to push harder on the gas pedal, and the torque converter clutch would unlock on my way up that hill.
The rings on my engine probably don't seal well enough with 5w20, so it will #30 viscosity from now on. The 5w20 was also getting dark faster than 5w30 normally does.
There's a small hill that I have to climb, and with 5w30, I can make it without pressing on the gas pedal hard enough to cause the torque converter clutch to unlock. With 5w20 in the engine, I almost always had to push harder on the gas pedal, and the torque converter clutch would unlock on my way up that hill.
The rings on my engine probably don't seal well enough with 5w20, so it will #30 viscosity from now on. The 5w20 was also getting dark faster than 5w30 normally does.
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