Does an engine run cooler with Syn in it?

[Al]

The friction coefficients of an ester might be slightly better than dino or syn. But the differences between an of them are probably extremely small. The only reason that syns can get better efficiency is if the viscosity can be reduced which can be possible in some applications.

My answer is "no"

 

[Gary Allan]

Complicated topic. I'd say that thinner oils (which a synth would not necessarily be after full warm up) reject heat better over cooling surfaces and would produce less heat do to easier shearing. I have a much harder time reaching normalized coolant temp with Bruce's 0w-10. It warms up okay, but sits locked below where it is for a 5w-40. I've got an exchanger ..so I'm bleeding heat off in one direction or the other depending on which is hotter. It still translates to lower coolant temps over the same service without the two working in concert.

A decent amount of cooling is done via the oil.

 

[tig1]

Isn't that why Corvette droped their oil cooler and went to M1 5-30 factory fill in the 90s?

 

[Al]

Originally Posted By: tig1
Isn't that why Corvette droped their oil cooler and went to M1 5-30 factory fill in the 90s?

They dropped it bc synthetics at the time could withstand at least a 50 degree higher temp than dino's.

 

[tig1]

In the 70s I tried Amsoil for a while and they said synt would decrease crank case temps by 20 degrees. Anything to it?

Al,
Seems like all the more reason to use synt. oil.

 

[lazaro]

I can cook mineral oil on my stove with around 375 degrees and in 3 minutes.
mineral oil turns to smoke,fire,caked on sludge.
I can do the same with Synthetic oil and at 500 degrees for 20 minutes I still have oil in the pan that still looks like oil.
I would say synthetic oil will keep any engine crankcase components considerably cooler than mineral oil can period!

 

[Steve S]

Originally Posted By: tig1
Isn't that why Corvette droped their oil cooler and went to M1 5-30 factory fill in the 90s?
G.M. lost a bunch of Vette engines during a Kentucky cold spell. The engineers figured with syn oil the oil cooler could be removed with the use of syn oil.

 

[BuickGN]

Besides the water temp, how can oil temps go down with synthetic? The vast majority of heat in the oil is from the piston crowns and flowing over the heads. I doubt there is enough reduction in friction, if any over to actually measure a heat difference.

Now if there is a heat exchanger involved, who knows, maybe synthetic transfers heat better. But this still wouldn't effect the coolant temps unless it was already struggling to stay at the thermostat opening.

 

[Mark888]

Originally Posted By: Steve S
Originally Posted By: Mark888
Originally Posted By: lucerne06
I changed my oil to a syn blend and it seems to be running a few degrees degrees cooler. According to temp gauge ..Is that possible?

Yes, it is possible.
How is it possible?

I can read my temperature gauge, and I have seen it happen on my last two cars when I switched to synthetic at my first oil change.

Those who believer that synthetic is a waste of money will never accept this. Suit yourself.

 

[BuickGN]

Originally Posted By: Mark888
Originally Posted By: Steve S
Originally Posted By: Mark888
Originally Posted By: lucerne06
I changed my oil to a syn blend and it seems to be running a few degrees degrees cooler. According to temp gauge ..Is that possible?

Yes, it is possible.
How is it possible?

I can read my temperature gauge, and I have seen it happen on my last two cars when I switched to synthetic at my first oil change.

Those who believer that synthetic is a waste of money will never accept this. Suit yourself.


So your thermostat magically opens at a lower temp with synthetic? Where is it reducing heat? A very small percent comes from friction. The rest is what the oil picks up from the pistons and heads. So how does this change in temp happen?

I'm a synthetic user, but this is not one of the reasons I use it.

 

[SnakeOil]

Guys this is very, very, VERY, simple.

Synthetic base stocks typical have a 5-10 percent advantage in terms of specific heat capacity than a conventional base. This is the amount of energy is takes to heat a unit of fluid one degree versus another. That said, it takes more energy to take a synthetic up to 200 degrees from 80 degrees than a conventional.

Secondly, synthetics have a higher heat transfer coefficient. Needless to say, they transfer heat to other materials faster and absorb the heat faster. That means they can absorb the heat from the head and crowns faster and then get rid of it quicker in the oil pan or oil cooler.

Combine this with reduced friction and other magical properties and you have a winner.


If you didn't know, then you didn't know. That's fine. But please don't refute years of research. There is a reason that Amsoil, RP, Mobil, Penz, Castrol, Valvoline, QS, ect.... ALL say that their synthetics reduce engine temps.

My $ .02

 

[BuickGN]

That actually makes sense. I figured if synthetic reduced some temps, it was because of better heat transfer.

I still don't buy the coolant temp running cooler unless it was already struggling to maintain temp.

I know that when I installed an oil cooler, it actually dropped coolant temps just a little but my car up until recently was never able to maintain the 160 degree thermostat setting.

 

[Mark888]

Originally Posted By: BuickGN
So your thermostat magically opens at a lower temp with synthetic? Where is it reducing heat? A very small percent comes from friction. The rest is what the oil picks up from the pistons and heads. So how does this change in temp happen?

I'm a synthetic user, but this is not one of the reasons I use it.

I didn't say that I use synthetic because it reduces engine temps at operating conditions. From what I can tell the difference is small and just barely noticeable on my gauge. But I did notice it, and thought I should say so. Others have also noticed it. I suspect that the slight reduction in engine temps is related to other good things going on in my engine with a synthetic as opposed to a conventional oil.

But like Joubert (Three Days of the Condor), I never ask "why?", only "who, when, and how much?" Always "how much?"

 

[smokey1]

when put synthetic oil in a 2000 CHEVY Prizm ( Corolla ) the temp gauge read about 3/16 of an inch lower than when using convenventional . The downside was it started to consume oil with a synthetic , went back to conventional and it came to a halt . Also , put MOBIL 1 A.T.F. in the PRIZM power steering unit and the level on the P.S. resorvoir read little over half mark on hot summer days , before that would read at the FULL mark with regular T.F. . So , tells me helps reduce friction which in return lowers the expansion of the molecules in A.T.F. fluid . Therefore , should apply to all applications . Last , I would think that a synthetic oil would reduce friction ( heat ) which is displaced in the engine block , that is carried away by the coolant , thus lowering the needle on the temp display . Anything's possible .

 

[CompSyn]

Calling Tom NJ...

Tom has said that synthetic oils high in Group V Ester oil additives plays a greater role in reducing the coefficient of friction, much more than what the oil base stock can do.

A high quality synthetic formulated high in Ester additives can reduce engine operating temps. There are many endurance racers that have found this out first hand.

 

[BuickGN]

Oil temps, maybe. Remember that thing called a thermostat?

 

[smokey1]

seems to me that the thermostat is like that of a faucet , allowing the flow of a fluid at certain speed . Which opens further as temps rise . No ?

 

[CompSyn]

Originally Posted By: BuickGN
Oil temps, maybe. Remember that thing called a thermostat?


To help paint the picture, I'm quoting this from another automotive forum for what it's worth:

"I work on an offroad race truck and we run oil temp gauges and found the following:
during a fifteen minute race our oil temps would get up to 300+ if using any non synthetic oils
Mobil one dropped the oil temps by about twenty degrees to 280 and switching to amsoil we dropped it to about 250-260 .......this is not representative of everyday usage but keep in mind that the water temp stays always inbetween 180-200 at all times no matter which oil.....so all in all it is kind of an accepted opinion that Mobil 1 is the cheapest and least effective of the synthetics but all of the higher end oils.......Amsoil, Royal Purple, etc. work better under extreme conditions. I guess it all depends on what your uses are. I just have my own opinions formed because of the info stated above."

Your operating water temp staying constant is one thing, but what if your oil is baking to crisp inside your crank case, that's not a good thing.

Operating water temp... operating oil temp... both operating temps...

 

[SlugGunner]

Hi, I'm new to these forums but have been an automotive tech for 50+ years and retired as an ASE-CMAT (Master Tech) in '94. I'd like to clear up a misunderstanding on the 'purpose' or the THERMOSTAT in modern auto engines.

FIRST, it DOES NOT control or regulate engine temperature in an engine. It is only a part of the TOTAL COOLING SYSTEM used in automotive applications. The THERMOSTAT's main purpose is to bring the engine operating temperature to NORMAL OPERATING TEMP as quickly as possible. It does this by REMAINING CLOSED until it's minimum (starts to open) termperature is reached. This contains most of the heating coolant within the engine block and preventing its circulation thru the radiator portion of the cooling system until this temperature is reached. This temperature is usually 295 degrees F on most modern gasoline engines.... this has been determined to be the minimum desired operating temperature for effective emission control purposes. This is also normally the minimum temperature at which the ECM control system goes into "CLOSED-LOOP OPERATION".

Most modern liquid-cooled engines maintain a normal operating temperature in the range of 210-230 degrees F. Once the THERMOSTAT opens, it has LITTLE FUNCTION unless the coolant temperature drops below its rated temperature rating (195^), at which time it will begin to close and raise the temperature of the coolant in the engine block again. During the NORMAL OPERATING TEMPERATURE RANGE the coolant temperature is mainly controlled by the RADIATOR, TYPE OF COOLANT MIX/RATIO, RADIATOR COOLING FANS and AIR FLOW ACROSS RADIATOR FINS. Ambient air temp and humidity also have an effect in both HEATING and COOLING.

Hope this helps clarify this issue.

But, to get back to the subject of this discussion.... yes, it is possible for synthetic oil to lower engine tempertures. Mainly, this is seen in OIL TEMPERATURE (especially if you have an OIL TEMP GAUGE). I have seen this be as much as 30-40 degrees COOLER difference in racing applications. It has also given WATER TEMPERATURE GAUGE INDICATIONS of 10-20 degrees COOLER at the same time and conditions. Outside ambient air temperature and humidity can CHANGE THIS EFFECT CORRESPONDINGLY.

 

[smokey1]

thanks . Been puttering around with cars for nearly 20 something years . :- )