Just as an empirical tip when I do oil and filter change I ask for only 7 litres to be used. The manual says more.

With 7 litres the indication is on the second bar (out of 3) which is fine and without danger of overfilling. This applies to 997.2 engines. For 997.1 the quantities might be different.

If you have excess oil take some out until you are below maximum.
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