Here's a little question for your magical calculator or even log chart. Take the specs of Red Line 10w-30 and Schaeffer #703 and tell me which one flows better at -30C and by how much. I'm talking flow, not cranking. Flow is not published, but you should be able to calculate it right?
How to calculate vis@85C ?
- Thread starter Ken4
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No. the graph and formulas will only hold true when the oil behaves like what's referred to as a "Newtonian Fluid". Any common oil whether its gear oils or motor oils, synthetic or non synthetic exhibit this Newtonian flow between say 3 and 10,000 cSt (viscosity). At the extreme ends of the curves the formulas won't work. That's why specific values such as pour point, stable pour point, and CC Viscosity are given by testing.
An explaination on using log paper.
http://www.physics.uoguelph.ca/tutorials/GLP/
[ November 07, 2003, 12:19 PM: Message edited by: garyb80 ]
http://www.physics.uoguelph.ca/tutorials/GLP/
[ November 07, 2003, 12:19 PM: Message edited by: garyb80 ]
I guess you could mathematically calculate the visc at 85C using the VI, as that will roughly give the slope (or rate of change) between the 40C and 100C.
Dont ask me how to calculate it tho. But I reckon even just by using a linear analysis, thats pretty much close enough.
Dont ask me how to calculate it tho. But I reckon even just by using a linear analysis, thats pretty much close enough.
Patman
Staff member
Hey, somebody messed up at the assembly plant and put your steering wheel on the wrong side of the car!
The whole point of this thread being, a person can make an informed choice of engine oil viscosity if he knows the operating temperature of the engine's oil.
And, the oil temperature does not have to reach 100C or 212F (at sea level) for water to evaporate or seperate from the engine oil.
If it did, there would be a lot of long lasting engines running with white emulsified engine oil.
And, the oil temperature does not have to reach 100C or 212F (at sea level) for water to evaporate or seperate from the engine oil.
If it did, there would be a lot of long lasting engines running with white emulsified engine oil.
The problem I have is that you're just getting a "mean" or average oil temperature at the point of measurement (assuming that's accurate). From what I've read, motor oil goes through the biggest temperature fluctuations of any fluid...ie. it sees like 175F at the top piston ring to minus whatever your climate goes down to.
So, I'm guessing 85F is your average oil temp. at normal engine operating temp.
Secondly, you mentioned that the oil temps rise when the car is shut off. Can you comment? What does it rise to? Above 85F??
So, I'm guessing 85F is your average oil temp. at normal engine operating temp.
Secondly, you mentioned that the oil temps rise when the car is shut off. Can you comment? What does it rise to? Above 85F??
I've been blabbering about oil temp/viscosity for a while. This is one reason I have nothing against the 20wt Ford/Honda/Mazda oils. As long as oil temp is in control, viscosity will be too.
I also agree that instantaneous vs average oil temperature is rarely mentioned. But, if oil flow/control is good, hotspots shouldn't be a problem. Silkolene/Fuchs/Titan claim that the 0w20's improved flow improves cooling.
Patman, its because they drive on the wrong side of the road.
Anyone notice that the 4cyl camry takes a long time to warm up. How long does it take for all the moisture to vent off??? Was the Toyota sludging issue because of frequent short trips(moisture accumulation) or overly hots heads&oil that everyone assumes but noone has really proven?
I also agree that instantaneous vs average oil temperature is rarely mentioned. But, if oil flow/control is good, hotspots shouldn't be a problem. Silkolene/Fuchs/Titan claim that the 0w20's improved flow improves cooling.
Patman, its because they drive on the wrong side of the road.
Anyone notice that the 4cyl camry takes a long time to warm up. How long does it take for all the moisture to vent off??? Was the Toyota sludging issue because of frequent short trips(moisture accumulation) or overly hots heads&oil that everyone assumes but noone has really proven?
Dr T, it's 85C not 85F. My guess is that oil temps rise when I shut down bcos there is no cooling water running, so the engine temp surges up another 5C then cools down eventually.
I discovered that the OEM oil pressure sender location is not the ideal location for sensing oil temp. The reason is that the oil temp sender is not in direct flow of oil, which could explain why it takes so long to heat up the oil. It is recommended to place a special adapter near the oil filter and tap the temp from there, where the sender is in direct stream of oil flow.
I discovered that the OEM oil pressure sender location is not the ideal location for sensing oil temp. The reason is that the oil temp sender is not in direct flow of oil, which could explain why it takes so long to heat up the oil. It is recommended to place a special adapter near the oil filter and tap the temp from there, where the sender is in direct stream of oil flow.
I decided to abandon my above setup and go for more accurate gauges and senders, and proper oil temp sender location. It cost me a bomb, but these gauges are very advance. I can even record 3 minutes of playback! Set warnings. Replay peaks. And there are audible and visual alerts. This is an oil fanatics dream.
Normal oil operating temp is now 105C.
Max oil operating temp is now 109C.
Ambient temp 34C.
Oil pressure @ idle is now 0.8 barg.
When I redline, temp goes up. When I idle, temp goes down.
Some pics here:
Normal oil operating temp is now 105C.
Max oil operating temp is now 109C.
Ambient temp 34C.
Oil pressure @ idle is now 0.8 barg.
When I redline, temp goes up. When I idle, temp goes down.
Some pics here:
Patman
Staff member
Very nice! I need a setup like that in my Firebird!
Was this tap there before and what was there origionally? And how does it read temperature of the oil-does it recirc somewhere???
Nice setup
Seems like oil temperature is directly dependent on ambient temperature. Here are some results I took in the morning. Pampered city stop & go driving.
Normal operating oil temp: 99C
Ambient temp: 30C
60C = 7min
70C = 9min
80C = 12min
90C = 18min
95C = 21min
97.5C = 25min
100C = 33min
Normal operating oil temp: 99C
Ambient temp: 30C
60C = 7min
70C = 9min
80C = 12min
90C = 18min
95C = 21min
97.5C = 25min
100C = 33min
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