Porsche 911 GT3 R 2012 Technical Manual page 14

3.4.5. Digital oil level display
An optional oil level display is available (997.641.139.9A):
The car wiring loom is already prepared for use of this display. The
connector for the display is located in the area of the rear side-window on
right-hand side of the car.
The values indicated in percent on the display correspond to the following
information in liters:
 10% -> 0.2 liters
As a result, a value of 50 % means that 1 liter must be added to the oil
tank in order to achieve 100 % on the display.
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