I see posts from people from Las Vegas and elsewhere thinking they need a better oil at > 100F ambients. If a vehicle is operated under similar conditions (normal driving), how does ambient temperature become an issue if any engine cooling system generally maintains a stable engine operating temperature. I am asking what is the other variable in the equation.
How does high ambient temperature affect oil ?
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Originally Posted By: MKZman
I see posts from people from Las Vegas and elsewhere thinking they need a better oil at > 100F ambients. If a vehicle is operated under similar conditions (normal driving), how does ambient temperature become an issue if any engine cooling system generally maintains a stable engine operating temperature. I am asking what is the other variable in the equation.
Oil temperature increases with ambient temperature. How much varies by car.
I see posts from people from Las Vegas and elsewhere thinking they need a better oil at > 100F ambients. If a vehicle is operated under similar conditions (normal driving), how does ambient temperature become an issue if any engine cooling system generally maintains a stable engine operating temperature. I am asking what is the other variable in the equation.
Oil temperature increases with ambient temperature. How much varies by car.
Oil temperature is not controlled by a thermostat like the coolant. My WRX's sump oil temperature would run at 100F above ambient from about 40F to 90F. The stock oil-water cooler kept the oil form going much below 140F or over 200F. That's about two grades of oil from summer to winter.
Ed
Ed
From AEHaas Motor Oil 101 - http://63.240.161.99/motoroil/101.html
Quote:
Oils are chosen by the manufacturer to give the right thickness at the normal operating temperature of the engine. I will say this average oil temperature is 212 F, the boiling point of water. On the track that temperature is up to 302F. It is important to realize that these are two different operating environments and require different oils.
I will discuss driving around town first. Everything I say will be based on these conditions. At a later time I will discuss track conditions. Everything I say will be as accurate as possible without looking everything up and footnoting. I am trying to be general not ultra specific.
One thing that is no longer important is the ambient temperature. Older automotive owner manuals often recommended one oil for the summer and another for the winter. This is still necessary for air cooled engines but is no longer a consideration in pressurized water cooled engines. These engine blocks are kept at around 212 F all year round. The oil is around the same temperature as well. This allows for a single weight oil all year round. Again, this is not the same as on the track where the coolant temperature is slightly higher and the oil temperature is much higher.
*****
The engine is designed to run at 212 F at all external temperatures from Alaska to Florida. You can get in your car in Florida in September and drive zig-zag to Alaska arriving in November. The best thing for your engine would be that it was never turned off, you simply kept driving day and night. The oil thickness would be uniform, it would always be 10. In a perfect world the oil thickness would be 10 at all times and all temperatures.
Quote:
Oils are chosen by the manufacturer to give the right thickness at the normal operating temperature of the engine. I will say this average oil temperature is 212 F, the boiling point of water. On the track that temperature is up to 302F. It is important to realize that these are two different operating environments and require different oils.
I will discuss driving around town first. Everything I say will be based on these conditions. At a later time I will discuss track conditions. Everything I say will be as accurate as possible without looking everything up and footnoting. I am trying to be general not ultra specific.
One thing that is no longer important is the ambient temperature. Older automotive owner manuals often recommended one oil for the summer and another for the winter. This is still necessary for air cooled engines but is no longer a consideration in pressurized water cooled engines. These engine blocks are kept at around 212 F all year round. The oil is around the same temperature as well. This allows for a single weight oil all year round. Again, this is not the same as on the track where the coolant temperature is slightly higher and the oil temperature is much higher.
*****
The engine is designed to run at 212 F at all external temperatures from Alaska to Florida. You can get in your car in Florida in September and drive zig-zag to Alaska arriving in November. The best thing for your engine would be that it was never turned off, you simply kept driving day and night. The oil thickness would be uniform, it would always be 10. In a perfect world the oil thickness would be 10 at all times and all temperatures.
Oil runs hotter in the summer. The only way around this is if you have a big external cooler with a lot of reserve and a thermostat. The Ferrari in the post above probably has that. For most normal cars, oil temp varies with ambient temps even though water temp remains the same.
I have no doubt that oil temps vary a bit. The big question though, is does it vary enough to care about it? For modern cars, I'd guess "no" for 99% of the cases.
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My old Z31 300ZX Turbo had an oil temperature gauge along with coolant temp gauge,boost gauge,and oil pressure gauge. The oil temp gauge would always get hot when I`d do alot of turbo boosting,BUT the engine coolant temp would always remain cool.
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Originally Posted By: aquariuscsm
My old Z31 300ZX Turbo had an oil temperature gauge along with coolant temp gauge,boost gauge,and oil pressure gauge. The oil temp gauge would always get hot when I`d do alot of turbo boosting,BUT the engine coolant temp would always remain cool.
The factory FSM recommended a 20W50 oil in warmer climates.
My old Z31 300ZX Turbo had an oil temperature gauge along with coolant temp gauge,boost gauge,and oil pressure gauge. The oil temp gauge would always get hot when I`d do alot of turbo boosting,BUT the engine coolant temp would always remain cool.
The factory FSM recommended a 20W50 oil in warmer climates.
Originally Posted By: jpr
I have no doubt that oil temps vary a bit. The big question though, is does it vary enough to care about it? For modern cars, I'd guess "no" for 99% of the cases.
On the Buick which is the only car I have a guage in, going from winter, usually a little above freezing, to 100+ degrees, oil temp varied by almost half of the temperature difference.
Hard driving made the biggest difference. I could easily surpass summer temps with a little aggressive driving.
I have no doubt that oil temps vary a bit. The big question though, is does it vary enough to care about it? For modern cars, I'd guess "no" for 99% of the cases.
On the Buick which is the only car I have a guage in, going from winter, usually a little above freezing, to 100+ degrees, oil temp varied by almost half of the temperature difference.
Hard driving made the biggest difference. I could easily surpass summer temps with a little aggressive driving.
Originally Posted By: BuickGN
Originally Posted By: jpr
I have no doubt that oil temps vary a bit. The big question though, is does it vary enough to care about it? For modern cars, I'd guess "no" for 99% of the cases.
On the Buick which is the only car I have a guage in, going from winter, usually a little above freezing, to 100+ degrees, oil temp varied by almost half of the temperature difference.
Hard driving made the biggest difference. I could easily surpass summer temps with a little aggressive driving.
That's pretty much my experience, unlike the nonsensical Haas quote a few posts up that claims oil temperatures are constant because water temperature is constant.
Slow speed high load is even worse because you lose most of your cooling from air passing the oil pan.
Originally Posted By: jpr
I have no doubt that oil temps vary a bit. The big question though, is does it vary enough to care about it? For modern cars, I'd guess "no" for 99% of the cases.
On the Buick which is the only car I have a guage in, going from winter, usually a little above freezing, to 100+ degrees, oil temp varied by almost half of the temperature difference.
Hard driving made the biggest difference. I could easily surpass summer temps with a little aggressive driving.
That's pretty much my experience, unlike the nonsensical Haas quote a few posts up that claims oil temperatures are constant because water temperature is constant.
Slow speed high load is even worse because you lose most of your cooling from air passing the oil pan.
Water temperature can be held constant but as there is no thermostatic control on oil temperature, it is at the mercy of temperature differential (the hotter it is outside, the harder it is for oil to cool off) and load (higher load, higher oil temperature) as far as oil temperature determination.
I've always thought this as well. Where have y'all been?
But the good doc does have a point, though. If it's a big consideration why don't automakers make more of a deal about it. Only thing I can think of is some severe service qualifiers include ambient temps over 90 degrees.
But the good doc does have a point, though. If it's a big consideration why don't automakers make more of a deal about it. Only thing I can think of is some severe service qualifiers include ambient temps over 90 degrees.
couple of questions for the gallery:
* Does anybody consider an '84 Buick to be modern car?
* Does anybody believe there is no correllation amonf engine temperature, coolant temperature, and oil temperature?
* Does anybody consider an '84 Buick to be modern car?
* Does anybody believe there is no correllation amonf engine temperature, coolant temperature, and oil temperature?
at what consistant hot oil temps should one consider moving up a grade? for daily driving and also track use?
daily driving with a 2.4l turbo, oil temps are 195-210 degrees with GC, SSO, and redline 10w40. coolant temps are in the same range
at the track during a 30 minute session, the redline 10w40 didnt get over 245ish degrees. coolant temps between 200-212, the second fan kicks on high speed at 212 degrees
daily driving with a 2.4l turbo, oil temps are 195-210 degrees with GC, SSO, and redline 10w40. coolant temps are in the same range
at the track during a 30 minute session, the redline 10w40 didnt get over 245ish degrees. coolant temps between 200-212, the second fan kicks on high speed at 212 degrees
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I remember seeing a temp chart posted on here somewhere that showed 10W-30 having a range of -4F to +95F. Central CA around here during the summertime is pretty much 100F+ everyday. You see where I'm going with this right? I'm wondering if GM spec'd 10W-30 for temps from -4F to +95F and that they're thinking if the car is driven in temps above +95F, they'd just hope for the best. They know in order to keep the consumers from getting confused, they'd have to spec one grade. Should people go one grade up for ambient temps above 100F ?
Originally Posted By: MKZman
I am asking what is the other variable in the equation.
Air flow, engine speed.
Is "Extreme high ambient temps" on Mobil's list of severe service applications? Answer is no:
"Mobil Clean 7500 should not be used to extend drain intervals under certain consumer or commercial severe service applications involving racing, frequent towing or hauling, extremely dusty or dirty conditions, or excessive idling."
So better oil isn't needed, but it's only logical to me it's ok to go up one grade because the oil's pre-heated when the engine is started.
I am asking what is the other variable in the equation.
Air flow, engine speed.
Is "Extreme high ambient temps" on Mobil's list of severe service applications? Answer is no:
"Mobil Clean 7500 should not be used to extend drain intervals under certain consumer or commercial severe service applications involving racing, frequent towing or hauling, extremely dusty or dirty conditions, or excessive idling."
So better oil isn't needed, but it's only logical to me it's ok to go up one grade because the oil's pre-heated when the engine is started.
Seems to me the idea of an oil cooler enabling the oil to be at a more constant temperature makes sense. I have read before that oil pans and diff. pumpkins with cooling fins on them allow the oil to run cooler. I have a trans cooler on my Ford pickup F-150, and I'm on the original tranny. Makes me wonder if the addition of a temp. controlled oil cooler wouldn't be a good investment. As you can see, I was gonna drive this thing til I died. That is, until the price of gas went out of sight!
Originally Posted By: jpr
couple of questions for the gallery:
* Does anybody consider an '84 Buick to be modern car?...
Yes AND no. The 3800 engine was/is quite a good one. Assuming that's what you have, and also depends on whether the engine is carburetted or fuel-injected. In any case, I think you're better off with a thicker summer oil, perhaps a high mileage one. Or a 15W-40...
couple of questions for the gallery:
* Does anybody consider an '84 Buick to be modern car?...
Yes AND no. The 3800 engine was/is quite a good one. Assuming that's what you have, and also depends on whether the engine is carburetted or fuel-injected. In any case, I think you're better off with a thicker summer oil, perhaps a high mileage one. Or a 15W-40...
With experience people can determine how hot a grill is by how long they can comfortably hold their hand over the fire. One could do the same with something like the valve cover, where in cold temps it's nice and warm when placing the palm on the cover, but try doing the same in the summer when it's hot out after being on the highway going up a grade with the air on. You'll find it's a stunt for the likes of Jackmule. The next exercise is sitting down in front of a case of beer, and pondering for a long time if the engine oil is exposed to more thermal stress as ambient temps increase.
The coolant temps would increase past the usual 12 o'clock position in the 93 Taurus in the summer with the air on on long grades or in stop and go traffic. On the highway I'd turn the air off until hitting the top, but in stop and go traffic I'd sometimes have to turn the heating on to keep the engine temps down. The 2003 Dodge diesel has an excellent cooling system as it's designed for handling fairly high loads, but parts of the engine still get hotter in the summer / colder in the winter. Dodge sells a cover for the radiator for use in cold temps.
The coolant temps would increase past the usual 12 o'clock position in the 93 Taurus in the summer with the air on on long grades or in stop and go traffic. On the highway I'd turn the air off until hitting the top, but in stop and go traffic I'd sometimes have to turn the heating on to keep the engine temps down. The 2003 Dodge diesel has an excellent cooling system as it's designed for handling fairly high loads, but parts of the engine still get hotter in the summer / colder in the winter. Dodge sells a cover for the radiator for use in cold temps.
Originally Posted By: jpr
couple of questions for the gallery:
* Does anybody consider an '84 Buick to be modern car?
* Does anybody believe there is no correllation amonf engine temperature, coolant temperature, and oil temperature?
You're right, the "old" cars don't follow the laws of physics. My observations are invalid because my car was made in 1984.
There may be some correlation between coolant temps and oil temps but in my experience with a constant 165 degree water temp, oil still runs 195-220 degress regardless.
couple of questions for the gallery:
* Does anybody consider an '84 Buick to be modern car?
* Does anybody believe there is no correllation amonf engine temperature, coolant temperature, and oil temperature?
You're right, the "old" cars don't follow the laws of physics. My observations are invalid because my car was made in 1984.
There may be some correlation between coolant temps and oil temps but in my experience with a constant 165 degree water temp, oil still runs 195-220 degress regardless.
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