Oil temperature?

[kjbock]

Originally Posted By: Hokiefyd
This forum continues to be excellent, and one of the best on the internet. This discussion started from a rather innocent question, but the collective depth of knowledge at this forum is amazing. Keep it up, gents.


Agreed. This discussion is great, though I'm not sure if my original question has been answered. For a fixed application, let's use my N52 engine as an example. Does it make any difference to use an oil that runs 10-20F hotter (or cooler, either way) than another. So if Castrol 0W-30 runs at 210F and Mobil 1 0W-40 runs at 230F, does it matter?

Would more data be needed to really answer the question? (UOA?)

 

[A_Harman]

You have set up a very hypothetical situation, but for the temperatures you mentioned, 210F wouldn't be a challenging temperature for Castrol, and 230F wouldn't be challenging to M1. But I wouldn't expect the oils to run at those widely different temperatures under the same conditions, just because their viscosities were 10% different. (Castrol 12.2 @ 100C, M1 13.5 @ 100C.) If M1 0w40 were run at 230F, its viscosity would be 11.1, so it would actually have lower viscosity than the Castrol at 210F.

 

[Shannow]

I think that your question is a hypothetical, and not grounded in reality...not dissing it, but I doubt you'll see the 20F within a grade, or even across two grades.

e.g., I've been messing around with thermocouples and engines, and switching from a 15W40 (HTHS presumably above 4) to an "economy" 5W30, with an HTHS of 3.2, and am seeing very little change in oil temperature (and a little mileage improvement).

Per A Harman's post, bearings in particular are partly self regulating. With a thicker oil, there will be more drag, which will run slightly hotter, and reduce the viscosity until an equilibrium is reached (more to it than that, as thicker oil makes a thicker film, bearing has less eccentricity, and slightly lower heating than viscosity alone would dictate).

Extreme example here

switched from 5W20 to 20W60 in my mower, and oil temperature went from 87 to 97 (In winter down here)...which demonstrates that the thicker oil creates more drag, uses more power, and runs at a higher equilibrium temperature (equilibrium being the power used to shear oil, versus what heat the crankcase can move to the environment)

 

[Shannow]

Originally Posted By: kjbock
So if Castrol 0W-30 runs at 210F and Mobil 1 0W-40 runs at 230F, does it matter?

Would more data be needed to really answer the question? (UOA?)


Ahhh...re UOA.

In turbines, transformer, and hydraulics, applications which have low additive treat rates, an increase of 10C halves oil life when you get over 80C...but oil life is still 40,000 hour plus regardless.

In an engine, a 10,000 mile OCI is 300-400 ours of operation, a drop in the bucket in comparison. THe oil is highly additised, and other things like heating/cooling, fuel, blowby, condensation, catalytic action of wear metals, and a myriad of other things will kill the oil before 10-20F of operating temperature.

For turbine oil life "generics", look here
http://www.machinerylubrication.com/Read/537/predict-oil-life

 

[kjbock]

Originally Posted By: A_Harman
You have set up a very hypothetical situation, but for the temperatures you mentioned, 210F wouldn't be a challenging temperature for Castrol, and 230F wouldn't be challenging to M1. But I wouldn't expect the oils to run at those widely different temperatures under the same conditions, just because their viscosities were 10% different. (Castrol 12.2 @ 100C, M1 13.5 @ 100C.) If M1 0w40 were run at 230F, its viscosity would be 11.1, so it would actually have lower viscosity than the Castrol at 210F.


Yes, it is somewhat hypothetical, but it is based on claims people were making on other auto forums. They were making statements that the new oil they switched to is "better" than their old one because it runs cooler in their engine.

 

[kjbock]

Originally Posted By: Shannow
I think that your question is a hypothetical, and not grounded in reality...not dissing it, but I doubt you'll see the 20F within a grade, or even across two grades.

e.g., I've been messing around with thermocouples and engines, and switching from a 15W40 (HTHS presumably above 4) to an "economy" 5W30, with an HTHS of 3.2, and am seeing very little change in oil temperature (and a little mileage improvement).

Per A Harman's post, bearings in particular are partly self regulating. With a thicker oil, there will be more drag, which will run slightly hotter, and reduce the viscosity until an equilibrium is reached (more to it than that, as thicker oil makes a thicker film, bearing has less eccentricity, and slightly lower heating than viscosity alone would dictate).

Extreme example here

switched from 5W20 to 20W60 in my mower, and oil temperature went from 87 to 97 (In winter down here)...which demonstrates that the thicker oil creates more drag, uses more power, and runs at a higher equilibrium temperature (equilibrium being the power used to shear oil, versus what heat the crankcase can move to the environment)


Thank you. Appreciate the response. I didn't really think there would be a big change switching between two grades so close to one another, but thought it would be worthwhile to ask.

 

[Sonataman]

On PYB5w20 mine would normally run 195-200f but this latest batch has been running as high as 217f. Checked alignment and calipers and everything seems fine.