20wt oils, higher temperatures and oil coolers

[fdcg27]

Originally Posted By: StevieC
But I do know.

And it must obviously be a concern for Dodge if they have a Hot Oil message appear in the manual and a limp mode instituted at some point.

Chrysler apparently decided to run this engine closer to the edge than is typically the case for low-perf engines.
The limp-home mode should reassure you, since power output is greatly reduced to keep oil temps out of the danger zone, allowing the oil to cool at these reduced outputs.
You're also running an oil that's probably better than something off the shelf.
Installing an oil cooler would defeat the design goals Chrysler apparently had in mind with this engine.

 

[demarpaint]

Originally Posted By: OVERKILL
Originally Posted By: StevieC
But I do know.

And it must obviously be a concern for Dodge if they have a Hot Oil message appear in the manual and a limp mode instituted at some point.

A lot of engines now have oil temp castration mechanisms, seems to be par for the course with xW-20 spec'd rigs. The Mustang GT has it, for example, and can be triggered on a good track that gets the oil hot enough.


Ironic in a way isn't it? I mean the thinner oil is to help with better cooling, the usual things we discuss here, etc. But when it reaches its limit engine power is reduced. Or they suggest running a thicker oil for better protection and less problems if you plan on tracking the car or working it hard.

 

[FZ1]

Originally Posted By: StevieC
Just changed the oil and filter with Amsoil SSO 5w20 and an EAK15. Going to run it 6K Miles (10,000km) and do a UOA on a sample and see how the increased temperatures is affecting the oil. Then if needed I will install a cooler. If the oil is fine this length of time I will let it go for the whole OLM time limit and do another UOA.
Perhaps oem oil and air filters would provide better flow and cooler temps. You could also try some premium gas on a highway trip..... it burns cooler.

 

[Shannow]

Originally Posted By: demarpaint
Ironic in a way isn't it? I mean the thinner oil is to help with better cooling, the usual things we discuss here, etc. But when it reaches its limit engine power is reduced. Or they suggest running a thicker oil for better protection and less problems if you plan on tracking the car or working it hard.


Except it's heat transfer and flow rate don't change...it AN'T provide better cooling.

It provides less internal friction, which is why it's installed in engines in the first place.

Think lift/drag in wings.

More viscosity gives more "lift" (parts separation), with more "drag" (viscous friction)....mre viscous friction GENERATES more heat, the thinner oil doesn't "cool" better.

 

[StevieC]

Originally Posted By: FZ1
Perhaps oem oil and air filters would provide better flow and cooler temps. You could also try some premium gas on a highway trip..... it burns cooler.


Premium gas here is like $5/Gallon. I run typically middle grade when it's affordable but usually regular when prices are high. It does make a difference to the timing and temperatures seem to go up with the higher octane.

 

[FZ1]

Originally Posted By: Shannow
Originally Posted By: demarpaint
Ironic in a way isn't it? I mean the thinner oil is to help with better cooling, the usual things we discuss here, etc. But when it reaches its limit engine power is reduced. Or they suggest running a thicker oil for better protection and less problems if you plan on tracking the car or working it hard.


Except it's heat transfer and flow rate don't change...it AN'T provide better cooling.

It provides less internal friction, which is why it's installed in engines in the first place.

Think lift/drag in wings.

More viscosity gives more "lift" (parts separation), with more "drag" (viscous friction)....mre viscous friction GENERATES more heat, the thinner oil doesn't "cool" better.
Interesting. Thinner oil does run cooler,right?

 

[demarpaint]

Originally Posted By: Shannow
Originally Posted By: demarpaint
Ironic in a way isn't it? I mean the thinner oil is to help with better cooling, the usual things we discuss here, etc. But when it reaches its limit engine power is reduced. Or they suggest running a thicker oil for better protection and less problems if you plan on tracking the car or working it hard.


Except it's heat transfer and flow rate don't change...it AN'T provide better cooling.

It provides less internal friction, which is why it's installed in engines in the first place.

Think lift/drag in wings.

More viscosity gives more "lift" (parts separation), with more "drag" (viscous friction)....mre viscous friction GENERATES more heat, the thinner oil doesn't "cool" better.


Thanks for the clarification. Then it would be safe to say doesn't protect any better, or they wouldn't advise bumping up a grade for tracking or heavy duty use. I'm glad I made the change back to 30 grade oil, I'm sorry I didn't listen to myself from the beginning. The way my vehicles are used I'd rather stick with a 30 grade oil.

 

[Shannow]

Originally Posted By: FZ1
Interesting. Thinner oil does run cooler,right?


Thinner oil generates less "self" heating, and therefore should/does run cooler.

It's not the old "101" story about flow and "carrying away more heat" that most people get stuck with...there's less heat to carry...which is why they put it in.

 

[StevieC]

So then....

Wouldn't a 20wt that is kept at a cooler temperature than the manufacturer intended act more like a 30 weight at the full operating temperature in this instance assuming we can keep it warm to boil off moisture but cool enough to be thicker than intended?

This would allow quicker flow when cold but better protection when hot.

 

[FZ1]

Understand. Thanks,man!

 

[Shannow]

Originally Posted By: StevieC
So then....

Wouldn't a 20wt that is kept at a cooler temperature than the manufacturer intended act more like a 30 weight at the full operating temperature in this instance assuming we can keep it warm to boil off moisture but cool enough to be thicker than intended?

This would allow quicker flow when cold but better protection when hot.


A 0W30 has the same requirements for pumpability at -35C as a 0W20...

At freezing, say, there's negligible (if any) difference between the grades.

 

[StevieC]

Sorry I didn't mean at freezing I meant in the warm-up stage. 20wt would warm quicker on short trips than a 30wt is what I was getting at.

 

[zeng]

Originally Posted By: fdcg27
Originally Posted By: StevieC
But I do know.

And it must obviously be a concern for Dodge if they have a Hot Oil message appear in the manual and a limp mode instituted at some point.

Chrysler apparently decided to run this engine closer to the edge than is typically the case for low-perf engines.
The limp-home mode should reassure you, since power output is greatly reduced to keep oil temps out of the danger zone, allowing the oil to cool at these reduced outputs.
You're also running an oil that's probably better than something off the shelf.
Installing an oil cooler would defeat the design goals Chrysler apparently had in mind with this engine.


Excellent observation on OEM line of thought , fdcg27.
High operating oil temperture 'problem' could be mitigated by selecting an oil of thicker viscosity grade ,which I speculate, as originally 'intended' by the OEM engineers .

 

[zeng]

Originally Posted By: demarpaint
Originally Posted By: OVERKILL
Originally Posted By: StevieC
But I do know.

And it must obviously be a concern for Dodge if they have a Hot Oil message appear in the manual and a limp mode instituted at some point.

A lot of engines now have oil temp castration mechanisms, seems to be par for the course with xW-20 spec'd rigs. The Mustang GT has it, for example, and can be triggered on a good track that gets the oil hot enough.


Ironic in a way isn't it? I mean the thinner oil is to help with better cooling, the usual things we discuss here, etc. But when it reaches its limit engine power is reduced. Or they suggest running a thicker oil for better protection and less problems if you plan on tracking the car or working it hard.

Ironic, indeed.
As this policy-driven initiatives bring financial benefits to players like OEMs, oil and additive companies with poor consumers footing the bills.

 

[zeng]

Originally Posted By: Shannow
Originally Posted By: FZ1
Interesting. Thinner oil does run cooler,right?


Thinner oil generates less "self" heating, and therefore should/does run cooler.

It's not the old "101" story about flow and "carrying away more heat" that most people get stuck with...there's less heat to carry...which is why they put it in.


Shannow,
As I understand it from here , other than contributing lesser viscous frictional heat loss , a thinner oil (in xW20) possesses marginally higher coefficient of heat transfer.
However from the perspective of a total system heat loss in a vehicle travelling at say 50-70 mph,in relation to thicker oil (in xW30/40)and other energy losses like air drag ,tire rolling resistance etc ,I consider thinner oil gain in energy loss as insignificant ( and bordering on being statistical ) in overall proportions.

Note:In total vehicle energy losses, coefficients of heat transfer of oils has zero significance in evaluating system efficiencies.

 

[Shannow]

Originally Posted By: StevieC
Sorry I didn't mean at freezing I meant in the warm-up stage. 20wt would warm quicker on short trips than a 30wt is what I was getting at.


Actually, the thicker oil will warm more quickly...it generates more heat. See the curve of heat input as the engine warms up, and starts to thin ?



Here's similar with a couple of different grades.

fmep is frictional mean effective pressure...can be translated into power by multiplying by displacement and RPM, and multiplying by a constant...it's normalised to compare different engines.

So for a given road load, the engine doesn't have to work as hard on the thinner stuff, so total power generated is lower, and less heat goes into the oil.

 

[StevieC]

I think I need to test this theory. Since I have a temperature gauge for my oil.

 

[dave1251]

On a hot summer day in July around here it is normal for the Hemi in my Ram to reach 229F after hours at 80MPH. Even then after a few minutes at idle the oil temp will talk to around 216F. The Highest oil temp I have observed is 236F. Even then it is not more then a few minutes at WOT up a mountain.

 

[Shannow]

StevieC, please do...

I've found that by holding a lower gear, and keeping the revs at 2,500 to 2,800 while leaving town, I can markedly speed up engine warmup by the time that I hit city limits over letting "D" do the thinking.

 

[bbhero]

Yes sir, very true Shannow. I have done that with great success in my Altima. I use the manual mode and keep the rpms up and it gets much warmer than if in regular D mode.