seems that whether you are looking at time or temps or miles it takes APPROXIMATELY twice as long for the oil temp to catch up to coolant temp---
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After coolant reaches operating, is oil warmed up?
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Hi,
pezzy669 - It depends a lot on the intended application for the engine. It also depends on such things as lubricant sump capacity
A great advantage of the "oil/coolant" intercooler is that it prevents thermal shock at whatever level and assists greatly in uniformally warming up the lubricant
Some oil/air coolers are not thermostatically controlled and this can cause very low lubricant temperatures in some conditions
As an example a Porsche 928 V8 on an open road in an ambient of say -10C will have its integrated cooling systems in action - the thermostatically operated computor controlled air intake flaps will be closed, the computor controlled fans will be off, the oil and coolant thermostat's will be at around crack point with the lubricant rapidly reaching the required temperature via the coolant. No thermal shock and the lubricant will likely intermittently flow thru. The Core temperature will be ideal
The same engine operating at 40C will have the flaps at around half intake capacity and the thermostats at similar positions. Lubricant will flow thru the cooler "washing" about 10-15C from it - the core temperature will be ideal. The margin for more cooling capacity is maintained via the coolant and the position of the intake flaps/fans
So each engine family's case is a different scenario. In the case of large high speed diesel engines the need to warm the lubricant is a very real requirement - especially when you are heating up 35-40 litres!
pezzy669 - It depends a lot on the intended application for the engine. It also depends on such things as lubricant sump capacity
A great advantage of the "oil/coolant" intercooler is that it prevents thermal shock at whatever level and assists greatly in uniformally warming up the lubricant
Some oil/air coolers are not thermostatically controlled and this can cause very low lubricant temperatures in some conditions
As an example a Porsche 928 V8 on an open road in an ambient of say -10C will have its integrated cooling systems in action - the thermostatically operated computor controlled air intake flaps will be closed, the computor controlled fans will be off, the oil and coolant thermostat's will be at around crack point with the lubricant rapidly reaching the required temperature via the coolant. No thermal shock and the lubricant will likely intermittently flow thru. The Core temperature will be ideal
The same engine operating at 40C will have the flaps at around half intake capacity and the thermostats at similar positions. Lubricant will flow thru the cooler "washing" about 10-15C from it - the core temperature will be ideal. The margin for more cooling capacity is maintained via the coolant and the position of the intake flaps/fans
So each engine family's case is a different scenario. In the case of large high speed diesel engines the need to warm the lubricant is a very real requirement - especially when you are heating up 35-40 litres!
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Originally Posted By: pezzy669
That makes me wonder what is better?
Oil/coolant heat exchanger or oil to air cooler?
OIL:coolant exchangers tend to be more compact due to the density of the exchange medium. Air is a poor conductor of heat compared to liquid.
You can sleep in 85F air without cover. You will eventually shiver in water of the same temp.
That makes me wonder what is better?
Oil/coolant heat exchanger or oil to air cooler?
OIL:coolant exchangers tend to be more compact due to the density of the exchange medium. Air is a poor conductor of heat compared to liquid.
You can sleep in 85F air without cover. You will eventually shiver in water of the same temp.
Below is a quote from a thread titled Sump Oil versus Coolant Temperature by Molakule
The predicted sump (bulk) oil temperature versus the coolant temperature
was shown to be about 18 to 20 degrees C higher for the oil than for the coolant at 2,000 RPM WOT. At 4,000 RPM WOT, the oil sump temperature was about 50 degrees C higher than the coolant temperature. The slope for both RPM ranges was about 0.7 C/C, which means that on the average, the Oil Sump temperature is always 1.2 to 1.43 times higher than the coolant temp.
An interesting side-bar of the study was that the bulk oil temperature increased "only" 0.3 C for every 1.0 C increase in ambient (oustside) temperatures.
· Zoz, Steve, et. al., Engine Lubrication Model for Sump Oil Temperature Prediction
SAE Paper 2001-01-1073.
The predicted sump (bulk) oil temperature versus the coolant temperature
was shown to be about 18 to 20 degrees C higher for the oil than for the coolant at 2,000 RPM WOT. At 4,000 RPM WOT, the oil sump temperature was about 50 degrees C higher than the coolant temperature. The slope for both RPM ranges was about 0.7 C/C, which means that on the average, the Oil Sump temperature is always 1.2 to 1.43 times higher than the coolant temp.
An interesting side-bar of the study was that the bulk oil temperature increased "only" 0.3 C for every 1.0 C increase in ambient (oustside) temperatures.
· Zoz, Steve, et. al., Engine Lubrication Model for Sump Oil Temperature Prediction
SAE Paper 2001-01-1073.
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Hi,
Gary - Correct IMO. Much depends on the engine family and its ancillaries and its installed application (frontal area etc etc) and operational intent. These are part desin stage matters
My Detroits showed an overall running average variance of 16C (coolant 87C and lubricant 103C) taken off the ECM downloads. The widest operational variance was 22C and the closest 5C
In this family the "normal" oil temps are up to 110C (96C), Warning 1 is at 115C (100C)and engine powerdown/shutdown occurs at 121C (106C) (Coolant limits are in brackets)
In my experience with V8 Porsche engines the variances are much less. This is partly due to the light metal block/head structures and overall design (cooling and lubrication systems) of that engine family
The highest bulk oil temps I have recorded was from a VW (Golf variant) at 132C - max allowed was 135C. BMW allowed oil lemps up to 135C I believe. In some prototype engines we have run with oil temperatures of above 150C for long periods
Gary - Correct IMO. Much depends on the engine family and its ancillaries and its installed application (frontal area etc etc) and operational intent. These are part desin stage matters
My Detroits showed an overall running average variance of 16C (coolant 87C and lubricant 103C) taken off the ECM downloads. The widest operational variance was 22C and the closest 5C
In this family the "normal" oil temps are up to 110C (96C), Warning 1 is at 115C (100C)and engine powerdown/shutdown occurs at 121C (106C) (Coolant limits are in brackets)
In my experience with V8 Porsche engines the variances are much less. This is partly due to the light metal block/head structures and overall design (cooling and lubrication systems) of that engine family
The highest bulk oil temps I have recorded was from a VW (Golf variant) at 132C - max allowed was 135C. BMW allowed oil lemps up to 135C I believe. In some prototype engines we have run with oil temperatures of above 150C for long periods
What happens when you throw in VTEC? I understand that the oil viscosity has an impact on how the VTEC engines work and I would think that getting on the gas before the oil warms up is not a good idea... I don't have a good understanding of how these work but I would think it would be another variable...
I have '04 S2000, I try to stay below 3k RPM for the first mile and increase 1k every mile after, i.e., below 4k second mile, below 5k third mile, below 6k fourth mile. After 5 miles I'll engage VTEC at more than 6-8k after 5 miles.
Hi,
John K - Not so much a variable John as a reason. This is just one reason why car makers like Mercedes Benz and Porsche only Approve synthetic lubricants. Those that have superior cold flow charcteristics are used as Factory fill
John K - Not so much a variable John as a reason. This is just one reason why car makers like Mercedes Benz and Porsche only Approve synthetic lubricants. Those that have superior cold flow charcteristics are used as Factory fill
Originally Posted By: byez
For the record I have discovered that the RX8's oil cooler ARE thermostatically controlled.
zoomzoom, very interesting graph, is this on a RX8?
It kind of scares me as the low 20's would be a very mild winter temperature for me. Could anyone extrapolate the graph information and calculate warm up from 0 degrees Fahrenheit and only city driving?
It seems that covering up the radiator to slow airflow into the engine bay would be a good idea. Would it still be possible to overheat or would the radiator fan just kick in more often?
no it is 2001 Audi S4..I would think warm up slope would be the same just start at lower temp...
For the record I have discovered that the RX8's oil cooler ARE thermostatically controlled.
zoomzoom, very interesting graph, is this on a RX8?
It kind of scares me as the low 20's would be a very mild winter temperature for me. Could anyone extrapolate the graph information and calculate warm up from 0 degrees Fahrenheit and only city driving?
It seems that covering up the radiator to slow airflow into the engine bay would be a good idea. Would it still be possible to overheat or would the radiator fan just kick in more often?
no it is 2001 Audi S4..I would think warm up slope would be the same just start at lower temp...
i have a cyberdyne oil temp gauge, 02 camaro w/LS1 v-8, all aluminum engine, holds 6 qts. temp sender is above oil filter, which is on the output side of the oil pump. I am not measuring sump temperature, and the sender is 3" away from the catalytic converter and it gets heated by that to read falsely high when it's hot out.
I've noticed that outside temp plays a very big part in how fast the oil warms up, if its > 75F outside then after 5-10 minutes the coolant is at 195F and the oil temp is just hitting 100F and takes another 10-20 minutes or 10 miles at 1500-2500 rpm driving for it to catch up at 200F.
On cold days when it's 40F or lower it takes a real long time. I have let the car idle in the driveway for 20 minutes, coolant at 195-215F and the oil is just hitting 80F; and I can drive to work which is 15 miles, 11 miles of it on the highway in 6th at 1500 rpm and the oil temp will just get to 190F as I get to work.
I've noticed that outside temp plays a very big part in how fast the oil warms up, if its > 75F outside then after 5-10 minutes the coolant is at 195F and the oil temp is just hitting 100F and takes another 10-20 minutes or 10 miles at 1500-2500 rpm driving for it to catch up at 200F.
On cold days when it's 40F or lower it takes a real long time. I have let the car idle in the driveway for 20 minutes, coolant at 195-215F and the oil is just hitting 80F; and I can drive to work which is 15 miles, 11 miles of it on the highway in 6th at 1500 rpm and the oil temp will just get to 190F as I get to work.
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