Porsche 2012 911 GT3 CUP Technical Manual page 59

5.9.4. Clutch layout
5.9.5. Release bearing
When handling the clutch release bearing-seal care must be taken that
absolutely no oil comes into contact with the seal, otherwise it can swell
which, in the worst case, could lead to a loss of function.
It should also be noted that when handling the seal the hands and working
area should clean and free of oil residue (this also applies for engine and
other oils).
According to the manufacturer the seal is only compatible with DOT4 and
DOT5 hydraulic fluids.
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