Slow Oil Temp Heat Up?
11-22-2012 | 12:40 AM
#16
Pro
Joined: Jul 2004
Posts: 677
Likes: 3
From: Minnesota
Does it really work this way? I don't know? Is the temp true or flake?
11-22-2012 | 12:43 AM
#17
Race Director
Joined: Sep 2006
Posts: 19,032
Likes: 256
From: Centerton, AR
My dealer told me that the oil temp reading has many factors before showing the actual reading. The sensor sends the reading to the computer, and it compares and shows on the guage by time . It determines the initial temp at start up. Then shows on the guage when it is in the low 100 degree range. Thats as much of it as I remember. I know I dont try to depend on it untill it is over the 190 - 200 range.
The sensor is a thermister which generates a voltage level based on temp. In pre-997 models this resides in the tip of the oil temp/level sensor tube which mounts on top of the engine and extends down into the oil sump or is in the oil tank in case of the Turbo engine.
This voltage level is fed to the DME which converts this from an analog value to a digital value.
This digital value is sent to the instrutment cluster controller which converts it back to an analog signal which is used to move an oil gage temp needle around.
Unless of course the oil temp is digital in which case the digital value is used to light up the appropriate number segments in the display to create the numbers that represent the oil temperature.
These engines are quite cold blooded and take time to reach full operating temperature. 10 or even 15 minutes of moderate driving on a mild day is often not long enough if one is really able to see the coolant temp. Also, even though the coolant temp is up to temp so to speak the oil temp lags behind some.
11-22-2012 | 12:54 AM
#18
Pro
Joined: Jul 2004
Posts: 677
Likes: 3
From: Minnesota
In 1963 I bought a new Corvette. Since I was developing temp controls at the time I put a thermocouple in the oil drain plug and ran it to a meter in the car. The oil temp rise vs water temp rise looked very similar to what I see in my 997.
11-22-2012 | 02:27 AM
#19
Drifting
Joined: Feb 2012
Posts: 2,612
Likes: 416
From: Raleigh, North Carolina
Maybe in the Porsche world.
My Ferrari 365 GTC/4 holds 19 quarts of oil. Sometimes it takes a good 20 minutes to get the oil temp needle to move. Once eveything is hot, the oil temp pretty much mirrors the water temp. Since the motor has no coolant thermostat, on cold days that means neither of the fluids will go over 180 degrees.
Makes DIY oil changes real fun..... you will only make the misatke of using a standard drain pan once.
My Ferrari 365 GTC/4 holds 19 quarts of oil. Sometimes it takes a good 20 minutes to get the oil temp needle to move. Once eveything is hot, the oil temp pretty much mirrors the water temp. Since the motor has no coolant thermostat, on cold days that means neither of the fluids will go over 180 degrees.
Makes DIY oil changes real fun..... you will only make the misatke of using a standard drain pan once.
