Is thicker synthetic run cooler?

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Some say yes some say no. Is syns are better for heat dissipation?
Is thicker syns like 10w30 vs 5w20 will run cooler?

Is thicker dino would do the same job?
Lots of combination....
 
The thicker the oil, the more friction it'll generate as it is being pushed around the engine. More friction = higher temps.
 
Unless you have a temp gauge that's calibrated in tenths, you'll never be able to tell any difference...
 
Ignoring viscosity maybe. Both PAO's and Esters have a higher thermal capacity than group 1, 2 or 3 base stocks. So in theory yes they could more effectively move heat. But in application I doubt they do, and most synthetics are group 3's which have the same thermal capacity as a conventional.

I would assume a thicker oil would always produce more resistance and therefore heat, but I suppose a thick oil could use a lot of friction modifier and that might not be true. For example Mobil 1 racing uses a huge amount of moly that might allow a thicker oil to run as cool as a normal oil of a lighter grade.
 
Originally Posted By: wolf_06
Some say yes some say no. Is syns are better for heat dissipation?


By a very small margin, possibly.


Originally Posted By: wolf_06
Is thicker syns like 10w30 vs 5w20 will run cooler?


Absolutely not. Viscosity is going to dominate the equation of how hot an oil runs, by far.
 
I've heard yes and no.
Thick absorbs more heat to carry it away, thin carries it away faster. I dunno.
Many say synthetic is less friction for cooler oil temp
Mostly in the motorcycle world hear synthetic runs cooler over dino - but don't recall grade/temp relationship
 
Specific Heat Index describes how much heat (energy) is required per unit mass to change the temperature of something by a unit temperature. It takes more heat to change the temperature of water than to change the temperature of aluminum for example. I don't know the trends of different base oils for this parameter.

The higher the Heat Index, the more heat a fluid can carry away.

The ability to conduct heat affects how fast a fluid can absorb heat. The higher the heat conductivity(at a fixed flow rate), the faster a fluid will absorb heat until equilibrium is reached. Aluminum is a better conductor of heat than styrofoam for example. I think that polar fluids tend to win-out for this parameter.

Thermal stability describes the ability of a material to tolerate higher temperatures without degrading or reacting with oxygen. In this parameter, Group III, PAO, and esters beat Groups I and II.

The viscosity determines how much fluid can flow through the engine only when the circuit is in bypass mode. Low viscosity fluids will cool better because they flow better without building pressure.

I do not know what "thermal capacity" means as it is used in bepperb's post above.


So, if your pump is in bypass mode often, low viscosity fluid will cool faster. High viscosity will produce heat from internal friction (as stated by others above). However, without knowing the conductivity of heat and the heat index, I don't think that this question can be answered. I guess that some of the formulators will know the relative values for different formulations.
 
A thicker oil would be more resistant to flow, would flow less, and therefore remove less heat than a thinner oil. The thinner oil would flow more, moving through the engine faster, removing more heat (especially through an oil cooler). Not sure much of this would be noticeable, though!
 
Does this query pertain to the vehicle in your sig ?

Is there an actual issue that you're concerned with ?

Why are you considering anything other than what the owners manual suggests ?

Keith
 
Thicker oils run hotter.
Some is because of increased drag, and some from the thicker boundary layer on parts that inhibit cooling.
You will see a difference of about 10 deg F on the highway going from a 20-50 to a 10-40.
 
Ok guys,

Seems that thin dissipate better, but lets say a 5w20, dino or syns?

Which one absorb heat better? I would say syns right?
 
Why? That is like saying your brother can absorb a rear end beating better than you but does it really matter both of you are going to be sore.

A pure group IV or V fluid can handle higher temperature better but good luck finding a pure group IV or V fluid at a price that is palatable just about every PCMO on the market is a blend and for your engine if there is enough heat variation to make a difference you have other issues to worry about than synthetic versus conventional
 
Originally Posted By: dave1251
Why? That is like saying your brother can absorb a rear end beating better than you but does it really matter both of you are going to be sore.

A pure group IV or V fluid can handle higher temperature better but good luck finding a pure group IV or V fluid at a price that is palatable just about every PCMO on the market is a blend and for your engine if there is enough heat variation to make a difference you have other issues to worry about than synthetic versus conventional
your point is?
 
Originally Posted By: mechtech2
Thicker oils run hotter.
Some is because of increased drag, and some from the thicker boundary layer on parts that inhibit cooling.
You will see a difference of about 10 deg F on the highway going from a 20-50 to a 10-40.

Thicker oil pumps slower through an engine and therefore allows more heat to be retained in the bearings etc, so in theory thicker oil will run hotter. That said I have run everything from a 20W-50 to a 0W-20 in the same engine without a thermostatically controlled oil cooler and I have never noticed any increase in maximum oil temp's with a heavy oil or a reduction in maximum oil temp's with a very light oil.

I think the question is moot.
Simply run the correct viscosity oil for your application.
A 20wt oil is specified. Running a 30wt oil which is thicker than necessary would be counter-productive for a whole slew of reasons.
 
Originally Posted By: wolf_06
Originally Posted By: dave1251
Why? That is like saying your brother can absorb a rear end beating better than you but does it really matter both of you are going to be sore.

A pure group IV or V fluid can handle higher temperature better but good luck finding a pure group IV or V fluid at a price that is palatable just about every PCMO on the market is a blend and for your engine if there is enough heat variation to make a difference you have other issues to worry about than synthetic versus conventional
your point is?


Good luck finding a PCMO that makes a measurable difference.
 
Originally Posted By: bullwinkle
Only reason to use a thicker oil, as far as I'm concerned, is if there's enough bearing wear on a high mileage engine to lower hot oil pressure.
Yes. Pick an oil viscosity that matches the clearances in the engine. Fortunately for most of us, the engine design engineers have done the homework for us.

Use the specified viscosity unless there is a very good reason to change it.
 
If thicker oil circulates slower, it wold have MORE time to pick up heat.
I can pass my hand through a bonfire quickly and not hardly feel it. A slow motion would burn me.
 
Originally Posted By: mechtech2
If thicker oil circulates slower, it wold have MORE time to pick up heat.
I can pass my hand through a bonfire quickly and not hardly feel it. A slow motion would burn me.


True...

There have been several instances over the years that running without a thermostat in hot weather caused overheating because the coolant passed through through the radiator faster than it could be cooled...
 
Would you also try to cool yourself with the fan set to low, since is the air would have more time to absorb heat. Or, would you set the fan on high, since the heat would be carried away faster.

And, thicker oil circulates slower ONLY when the the pump is in bypass mode. This is why thicker oil produces more pressure until the bypass is actuated.
 
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