(I am not sure of the exact terminology) Oil doesn't transfer heat to itself very well. Water transfers heat (carries heat??) faster than oil.
Water vs Oil temperature.
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I have run a few hundred engines on the engine dyno. Almost all BBC engines and all high performance. Before performing full power pulls the engine oil temp needs to be 180 to 200F to assure the engine is fully warmed up and prevent spinning a bearing. Coolant temp dosent really matter, but is controlled to 160 to 180F.
It always takes quite awhile to heat up the oil compared to the coolant. You always have to put heat into the oil by loading the engine a fair amount. Sitting on the dyno at idle or high idle will not heat the oil enough.
So when you ask how long does it take to heat the oil, it depends on how you are warming it up. Under moderate load or idling?
I would definately take it easy on any engine until the oil is warmed up reasonably.
It always takes quite awhile to heat up the oil compared to the coolant. You always have to put heat into the oil by loading the engine a fair amount. Sitting on the dyno at idle or high idle will not heat the oil enough.
So when you ask how long does it take to heat the oil, it depends on how you are warming it up. Under moderate load or idling?
I would definately take it easy on any engine until the oil is warmed up reasonably.
Bump! Nice thread! My question is what happens when you have the heater on. In my car in gentle city driving water temperatures can actually drop, even go down to "low" by using the heater. What happens to oil temperatures in such conditions?
Originally Posted By: nickolas84
Bump! Nice thread! My question is what happens when you have the heater on. In my car in gentle city driving water temperatures can actually drop, even go down to "low" by using the heater. What happens to oil temperatures in such conditions?
It depends on your car. It sounds like your thermostat does not compensate quick enough.
What car do you drive? If that was happening in my car I would be considering replacing the thermostat.
In my E46 when I turn on the heater full heat, the coolant temp with drop maybe 5 degrees Celsius when I turn it on, but give it 10-15 seconds, and it will go back up to what it was before when the heater was off.
Likewise, when I turn off my heater, I can get the coolant temp to go up a few degrees, but the car quickly compensates, and the temp goes back down.
Bump! Nice thread! My question is what happens when you have the heater on. In my car in gentle city driving water temperatures can actually drop, even go down to "low" by using the heater. What happens to oil temperatures in such conditions?
It depends on your car. It sounds like your thermostat does not compensate quick enough.
What car do you drive? If that was happening in my car I would be considering replacing the thermostat.
In my E46 when I turn on the heater full heat, the coolant temp with drop maybe 5 degrees Celsius when I turn it on, but give it 10-15 seconds, and it will go back up to what it was before when the heater was off.
Likewise, when I turn off my heater, I can get the coolant temp to go up a few degrees, but the car quickly compensates, and the temp goes back down.
If you run a small engined car or a diesel, this can happen until the cabin is fully warmed up.
Once the cabin is warmed and the heater fan slowed down to it's normal pan the needle doesn't move from 90°c anymore but until then coasting definitely reduces the water temp in my 2.0 mjet. I drive very careful when the engine isn't fully warmed though, you won't see this if you drive as if the engine is fully heated.
What happens with the oil temp depends on the design of the coolant system, but generally speaking oil temp is more dependant on engine rpm than on load, the inverse is true for coolant temp.
Once the cabin is warmed and the heater fan slowed down to it's normal pan the needle doesn't move from 90°c anymore but until then coasting definitely reduces the water temp in my 2.0 mjet. I drive very careful when the engine isn't fully warmed though, you won't see this if you drive as if the engine is fully heated.
What happens with the oil temp depends on the design of the coolant system, but generally speaking oil temp is more dependant on engine rpm than on load, the inverse is true for coolant temp.
In general it is certainly true that the coolant will come up to temp faster. I wonder how much of a difference a turbo makes?
On my vehicles they are equipped with an oil to coolant oil cooler, which is thermostatically controled, and it still takes longer to heat the oil (engine & transmission), but its much faster than an engine with no cooler equipped.
Oil and water temps are one of the main reasons I have an Edge CTS monitor on my truck. On the 6.0 Powerstroke diesel, the oil temp should never get more than about 15 degrees above the coolant temperature (cruising at 65 mpg on flat level ground, no trailer). If it does, that's a sign that it's due for an oil cooler.
Cruising, my coolant temp stays at 192, oil at 196.
Cruising, my coolant temp stays at 192, oil at 196.
Originally Posted By: Michael_P
One thing I have noticed on my wifes new car. On a super cold day (close to 0°F), the coolant temp stays constant but the oil temp will run as much as 30° colder than on a 70° day. This is after the car has run for over 1/2 hour.
That is interesting. The coolant is constant at the normal level (say 190F or whatever it is?)? Are you using the heater?
One thing I have noticed on my wifes new car. On a super cold day (close to 0°F), the coolant temp stays constant but the oil temp will run as much as 30° colder than on a 70° day. This is after the car has run for over 1/2 hour.
That is interesting. The coolant is constant at the normal level (say 190F or whatever it is?)? Are you using the heater?
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My Vehicle's coolant temp gauge is actually representative of coolant temps, and not a dumbed down version that is standard on later models so that wider and normal swings of the needle do not freak out today's buyers.
I also have a mechanical oil pressure gauge.
While my coolant temp gauge will goto the normal range fairly quickly, my oil pressure gauge lags considerably before I can tell the oil is as hot as it can get, in normal driving, and it takes at a minimum of 25 minutes for it to read as low as it gets at any given rpm whereas the coolant temp gauge is at the midway mark within 5 minutes or so.
I also have a mechanical oil pressure gauge.
While my coolant temp gauge will goto the normal range fairly quickly, my oil pressure gauge lags considerably before I can tell the oil is as hot as it can get, in normal driving, and it takes at a minimum of 25 minutes for it to read as low as it gets at any given rpm whereas the coolant temp gauge is at the midway mark within 5 minutes or so.
25min for the oil and 5min for the water is with the heater off?
I suppose the heater has an effect on water temperature (it takes much longer for the water temp. to go up on my car with the heater on) but does it affect the oil temperature, and how long it takes to heat it up?
I suppose the heater has an effect on water temperature (it takes much longer for the water temp. to go up on my car with the heater on) but does it affect the oil temperature, and how long it takes to heat it up?
Depends on the engine design. what engine are we talking about?
If it's a turbo engine there will most likely be an oil/coolant heat exchanger.
I put the heater on 16°C until the coolant has reached 90°C, then I change the cabin temp to 20-22°c depending on what jacket I'm wearing. It makes the engine heat up about 2 minutes faster: 28 minutes iso 30....
I have a turbo diesel though, and traffic conditions due to intensive roadworks in the neighbourhood means I sit more time idling than driving, and when traffic does start to move I'm going downhill and can just coast down.
If it's a turbo engine there will most likely be an oil/coolant heat exchanger.
I put the heater on 16°C until the coolant has reached 90°C, then I change the cabin temp to 20-22°c depending on what jacket I'm wearing. It makes the engine heat up about 2 minutes faster: 28 minutes iso 30....
I have a turbo diesel though, and traffic conditions due to intensive roadworks in the neighbourhood means I sit more time idling than driving, and when traffic does start to move I'm going downhill and can just coast down.
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