Viscosity and climate

[Garak]

Originally Posted By: Shannow
Which allows the bulk oil temperature to exceed the thermostatically controlled coolant temperature, and under extreme conditions by a significant margin.

Thanks for reminding us of this. It's easy to forget that while the coolant circuit is fairly well governed to stay very close to a certain temperature (once warmed up, of course), oil temperatures fluctuate more and certainly aren't usually constrained quite to the narrow window that coolant temperatures are.

Of course, if one's driving a steady state 55 mph, one's oil temperature isn't apt to fluctuate much, even with a few degrees difference in ambient from test to test. In a similar vein, stepping on the gas isn't going to raise your coolant temperature to the point of overheating, either.

 

[bar1]

Originally Posted By: kr_bitog
...but in country like Brazil, China, Indonesia, Thailand this is daily scenario and it worsen by only low quality based engine oil available makes the thicker oil is necessary to fight the fuel dilution and ensure longevity the engine.


I've been to Brasil many times. PCMO there is top notch, Mobil1, Castrol, Petrobras Lubrax, BP, Shell, Total/Elf etc. Most popular grade seems to be 5W-40. All I've seen has been with ACEA A3/B4 spec, and some with VW/BMW/Porsche (or other euro mfg) approvals. Engine oil there is as good as in the US and/or Europe.

 

[CATERHAM]

Originally Posted By: lockguy
Im wondering why people tend to use a "thicker" or higher viscosity oil in hotter climate. The thermostat keeps the engine about the same operating temp whether in hotter or colder climates right?

To me, it is more of a decision of how much protection do you need vs effeciency savings...any thoughts?

It's not about using a thicker or higher viscosity oil in the hot summer months (or in a hotter climate generally) and therefore more protection but rather attempting to maintain a certain minimum operational viscosity.
Put simply, heavier oil grades may be necessary to compensate for the very much higher oil temp's that can occur with higher ambient temp's.
In vehicles with exposed sump's and without coolant/oil heat exchangers, the difference in maximum oils temp's can easily be as much as 50C or more between the frigid depths of winter and the mid-day heat under a blazing sun raising asphalt temp's to as much as 65C (and the above boundary air layer) of summer or more.

Every grade from 5W-20 to 20W-50 (0W oils weren't generally available yet) are specified for my older Porsche based largely on ambient temp's to try and achieve that same desired operational viscosity. Today it is just one grade that's recommended, 0W-40, for all ambient temp's and all Porsche engines (like many manufacturers) have coolant/oil heat exchangers. This greatly stabilizes maximum oil temp's so that the affect of ambient temp's is mitigated to a large degree.

 

[Shannow]

Originally Posted By: CATERHAM
It's not about using a thicker or higher viscosity oil in the hot summer months (or in a hotter climate generally) and therefore more protection but rather attempting to maintain a certain minimum operational viscosity.


Ummmmmmmm...yeah

So the higher (bottle label) viscosity offers more protection in a hotter climate, by providing a more optimal operational viscosity...

 

[fdcg27]

The usual term is "specific output".
The two liter S2000 makes 240 bhp, not 200.

 

[Shannow]

BMEP

 

[virginoil]

Originally Posted By: Shannow
Originally Posted By: CATERHAM
It's not about using a thicker or higher viscosity oil in the hot summer months (or in a hotter climate generally) and therefore more protection but rather attempting to maintain a certain minimum operational viscosity.


Ummmmmmmm...yeah

So the higher (bottle label) viscosity offers more protection in a hotter climate, by providing a more optimal operational viscosity...


Sounds like Australia's Penrite Oil +10 philosophy talking here.

 

[kr_bitog]

Originally Posted By: lockguy
Originally Posted By: Ducman
Originally Posted By: lockguy
Im wondering why people tend to use a "thicker" or higher viscosity oil in hotter climate. The thermostat keeps the engine about the same operating temp whether in hotter or colder climates right?

To me, it is more of a decision of how much protection do you need vs effeciency savings...any thoughts?


Hi Lockguy,

As already mentioned, a lot depends upon the application, design and power density of the engine.

You need to condider that within the engine there are some parts (for example valve train components in engines with flat tappet cams) that endure highly elevated point loading stresses and subsequently experience higher temperatures which are not reflected in oil temp gauges, or even remotely corelate to coolant temps as shown on the temp gauge.
These temps will seriously thin out a thicker oil in the immediate area, leaving only boundary layer lubrication to protect the parts as a last line of defence.
Boundary layer lubrication is only 1 part of the different phases of lubrication.

Some current owners manuals provide clear guidelines as to what oil viscosity you should run within given ambient temperature ranges for engines, transmission and diffs.

Also for example, Amsoil on their website recommend 5w30 oil for the engine in my car, but have a caveat written in to cover any application when ambient temps over 32 F occur, where they recommend a 10w30 oil.
There are currently no exceptions in their recommendations for this engine as utilized in my car.
The engine has a hydraulic roller camshaft, and in my car there is no oil cooler or oil/coolant heat exchanger.

Cheers


thanks for the intuitive post. It does make sense that at some parts of the engine might getter hotter due to stresses on that part. But....if for instance, a particular car was sold throughout the US, texas, louisiana etc, and it says on the cap, 5w-20, don't you think the engineers took that into account? Most owners manuals do not specify different weight oil depending on climate, i know i have not seen one.

if the thermostat keeps the coolant at 200 F, the engineers are anticipating that the engine is going to be a certain temperature. Im not sure that whether its 50F or 110F outside, the coolant is going to stay roughly the same 200F, therefore the engine will be within normal operating temperatures. I would think that the temperature of those particular parts will be roughly porportionate to the temperature of rest of the engine and/or the coolant. so if the coolant temp is consistant, so is the oil, so is the engine.






Have you heard term "tropicalized"? some cars have different cooling capacity for the radiator and aircon for different target market. Latest problem fir this is the vwdsg gearbox recall

 

[BlueOvalFitter]

Originally Posted By: HerrStig
Spare us ANOTHER "heavier/lighter" rant. I know what my owner's manuals say.

Hi, my username is BlueOvalFitter. I can't read so I have never read my owner's manual. I use 85W140 oil in my engine and upon startup it sounds like a woodpecker on a street light. Is this oil too light for my engine?

 

[OVERKILL]

Originally Posted By: fdcg27
The usual term is "specific output".
The two liter S2000 makes 240 bhp, not 200.


That's fantastic. It doesn't change the point of my post however. The engine also makes 153lb-ft of torque... at 7,500RPM. Which means it needs to be spun to the moon to get out of its own way. As is yet another caveat of using small displacement and high power density. If you don't have displacement, you need RPM.

This is why, despite having a lower power density, the Ford Roadrunner engine in the BOSS 302 (5.0L, 444HP) has the ability to heat the oil far more than the S2K does. And why it spec's 5w-50. Because in the end, it still has a 200HP advantage over the S2K, and that 200HP is working to heat the oil. It also makes 360lb-ft of torque at 4,500RPM, which means it can get out of its own way too

 

[CATERHAM]

Originally Posted By: OVERKILL

This is why, despite having a lower power density, the Ford Roadrunner engine in the BOSS 302 (5.0L, 444HP) has the ability to heat the oil far more than the S2K does. And why it spec's 5w-50. Because in the end, it still has a 200HP advantage over the S2K, and that 200HP is working to heat the oil. It also makes 360lb-ft of torque at 4,500RPM, which means it can get out of its own way too

But the still 400+hp Mustang GT gets by just fine on a 5W-20.

 

[CATERHAM]

Originally Posted By: Shannow
Originally Posted By: CATERHAM
It's not about using a thicker or higher viscosity oil in the hot summer months (or in a hotter climate generally) and therefore more protection but rather attempting to maintain a certain minimum operational viscosity.


Ummmmmmmm...yeah

So the higher (bottle label) viscosity offers more protection in a hotter climate, by providing a more optimal operational viscosity...

Not more protection but rather a greater operational viscosity reserve. That may be required if the oil temp's warrant it but will simply be more unnecessary oil drag if the oil temp's don't warrant it.

 

[fdcg27]

OTOH, the stock Honda will stay together at well over 9000 revs, which can't be said of the Ford.

 

[BlueOvalFitter]

Originally Posted By: fdcg27
OTOH, the stock Honda will stay together at well over 9000 revs, which can't be said of the Ford.


That is so much

 

[fdcg27]

Really?
Check the respective redlines of these engines.

 

[OVERKILL]

Originally Posted By: CATERHAM
Originally Posted By: OVERKILL

This is why, despite having a lower power density, the Ford Roadrunner engine in the BOSS 302 (5.0L, 444HP) has the ability to heat the oil far more than the S2K does. And why it spec's 5w-50. Because in the end, it still has a 200HP advantage over the S2K, and that 200HP is working to heat the oil. It also makes 360lb-ft of torque at 4,500RPM, which means it can get out of its own way too

But the still 400+hp Mustang GT gets by just fine on a 5W-20.


What is funny though is that if you add the "Track Pack", you get an oil cooler and a requirement to run 5w-50

Remember, the engine is also thermally castrated based on oil temp to allow you to use 5w-20

 

[OVERKILL]

Originally Posted By: fdcg27
Really?
Check the respective redlines of these engines.


Roadrunner has been tested to be stable to 8,400RPM. And at the end of the day, your 600RPM difference leaves >200HP on the table to the V8 and a 12 second vs 14 second time-slip at the end of the 1320.

 

[OVERKILL]

Originally Posted By: fdcg27
OTOH, the stock Honda will stay together at well over 9000 revs, which can't be said of the Ford.


I'm not sure where this even fits in this discussion? It sounds like so much bitter fanboyism. We are still talking about a >200HP difference between the two engines. Revin'g the 2.0L to 9 grand isn't going to help that problem.

"Yeah, your V8 only can rev to 8,400RPM? Well my 2.0L Honda engine can rev to 9,000RPM!"

It doesn't change the fact that we are talking about 240HP vs 444HP

 

[CATERHAM]

Originally Posted By: OVERKILL
Originally Posted By: CATERHAM
Originally Posted By: OVERKILL

This is why, despite having a lower power density, the Ford Roadrunner engine in the BOSS 302 (5.0L, 444HP) has the ability to heat the oil far more than the S2K does. And why it spec's 5w-50. Because in the end, it still has a 200HP advantage over the S2K, and that 200HP is working to heat the oil. It also makes 360lb-ft of torque at 4,500RPM, which means it can get out of its own way too

But the still 400+hp Mustang GT gets by just fine on a 5W-20.


What is funny though is that if you add the "Track Pack", you get an oil cooler and a requirement to run 5w-50

Remember, the engine is also thermally castrated based on oil temp to allow you to use 5w-20

Yes I know it's "thermally castrated" as you say, but that's a good thing! Lot's if not all recent cars likely are; i.e., have safety systems in place to prevent the oil getting too hot and therefore too thin. For most street driven cars the safety systems undoubtedly never kick in so you benefit from running a lighter oil a more appropriate optimized oil viscosity.

 

[fdcg27]

Originally Posted By: OVERKILL
Originally Posted By: fdcg27
Really?
Check the respective redlines of these engines.


Roadrunner has been tested to be stable to 8,400RPM. And at the end of the day, your 600RPM difference leaves >200HP on the table to the V8 and a 12 second vs 14 second time-slip at the end of the 1320.


Does Ford paint a redline of 8400 on the tach of any Mustang?
Don't think so.
The S2000 is capable of quite a bit more then fourteen second quarters. It just needs a driver who understands that the 9000 rpm redline is meant to be used and who knows how to shift.
Quarters in the thirteens are more typical with an experienced driver.
Pretty impressive for a normally aspirated stock two liter with all the mod cons.
Finally, if you want to compare apples to apples, the most potent stock Camaro will eat the most potent stock Mustang for lunch on any road course and spit out the seeds.
This has been shown time and again in a number of comparison tests. You could Google it.
The Mustang's Modular appears to be no match for pushrod Chevy power, although part of the reason is that the pushrod Chevy is so much more efficient in its use of space that it can be built to considerably larger displacement than can the OHC Ford while still fitting into something smaller than an Expedition.
More displacement and more power in a physically smaller package.
What's not to like, unless you're a Ford loyalist?