Engine Oil Temp

[FlyingHaggisRace]

Something of a thought exercise..


Imagine you can have an engine oil with the exact properties you wanted, independent of temp range.

What would those qualities be numerically ?

viscosity
Sheer
etc...


Given that an engine apparently likes to run with a water temp of 90C for ideal combustion.

Now imagine you can control the oil temp to be what ever you wished by having a controllable oil cooling solution.


So, what would be the ideal temp for the oil you are feeding back into the engine ?

 

[Volv04Life]

Thats really deep for your first post... I smell a troll

 

[nyumski]

Originally Posted By: FlyingHaggisRace
Something of a thought exercise..


Imagine you can have an engine oil with the exact properties you wanted, independent of temp range.

What would those qualities be numerically ?

viscosity
Sheer
etc...


Given that an engine apparently likes to run with a water temp of 90C for ideal combustion.

Now imagine you can control the oil temp to be what ever you wished by having a controllable oil cooling solution.


So, what would be the ideal temp for the oil you are feeding back into the engine ?




i thought we discuss about the oil temp device or something but it smells like a troll? i dont know

 

[Olas]

Look up a spec sheet for Redline 10w40 to see my ideal numbers.

Oil temp varies a lot between the sumo and the bearing but in the sense of your question I'd be happy with 90-100 degrees C.

 

[555]

Thin as water and reduces friction to zero.

 

[NGRhodes]

0W0, HTHS of 1 zillion, noack of zero, VI of 1 zillion, oil temperature absolute zero.

 

[FlyingHaggisRace]

Not a troll - sweet Jesus people are paranoid.

Let's rule out absolute zero or other extremes.

Let's say you live in a climate were the temp range is very small and stable.
For me the temp range is 25 - 35C, and for most of the year it will be 30-35C.

There is no need to have an oil that can deal with -10 in winter and +40 in Summer.

So given the very stable ambient range.
And given the ability to size the oil cooler and to set the oil thermostat as desired.

What would be the idle oil properties and oil operating temp ?

My own inclination is to perhaps run the oil temp somewhat cooler than 90C, and to absorb some heat into the oil.

 

[Dyusik]

I have mild climate, and never see sub 10f temps, above 100f summer is rear. A 10w30 is my voice for low stress engines in the Lexus family. The Jeep gets a the same, sometimes a 40 due to high rev uphill climbs that may take a while, I have burnt my hand on the hood trying to lift it after such events. 50 for air cooled. So ideally, a 10w30 full synthetic with no VII and an HD add pack would be my choice for where I live for the cars. The Yamaha seems to perform best with a 13-14 cst fluid. If only it would stay there longer than 1k miles ... the harley, I just pour molases, it's slow no matter what I do.

 

[ARCOgraphite]

Nascar (Sprint Cup or Monster!?) does this, IIRC, Start a cold engine with hot oil. Oil has it own heat exchanger to control temp (cool or heat).

I would start with a monograde 20 with high HTHS, cold start with oil at 15C controlled temp to 80C fully warmed.

Get some data, Go from there.

If you could do this you could re-clearance the engine and change bearing area for less windage.

Wonder how these cold sloppy pistons will feel about thin, hot oil BEFORE they start growing?
Slap, slap SLAP!
-Ken (Fellow Scot)

 

[oil_film_movies]

You ask what is the ideal temperature? 104 degrees C is about perfect for oil temperature. I saw this once on an Oil Life Algorithm calculation paper. Water generated by normal combustion and blowby is boiled off, increasing oil life. Its the perfect steady temperature. See page 18 (and also page 14) of https://etda.libraries.psu.edu/files/final_submissions/392

At those temperatures, the oil has to be thick enough to be hydrodynamic. Thats usually a KV100=10 and HTHS=3.0 for a lot of engines. It varies based on what engine we are talking about, only varying about plus or minus 20% of those viscosity values.

 

[FlyingHaggisRace]

Super, we are getting somewhere.

I'm certainly no expert, but if i may throw in a few items for comment.
And will read the above grad paper tonight.

1. Temp to remove water condensation.
There is a thread on this site, that seemed to suggest it was not necessary to get 100 or higher to get the water to evaporate such that it will remove the condensate.


2. If ideal values for KV100 and HTHS could be achieved at lower temps, then why not use lower oil temps ?

 

[Jetronic]

Originally Posted By: FlyingHaggisRace



2. If ideal values for KV100 and HTHS could be achieved at lower temps, then why not use lower oil temps ?





The oil heats up itself as it shears between the bearing surfaces. Higher RPM = hotter oil.

Most cars with oil/air coolers have a thermostat that opens at 80°C, but not all oil will be sent through the cooler. If not an oil/air cooler, there's often an oil/coolant cooler/heater.