Turn the knurled ring to 
.
The warning light 
on the instrument
cluster will come on.
See also:
Checking fluid levels
IMPORTANT When topping up take care not to confuse the various types of fluids:
they are all incompatible with one another and could seriously damage the car.
IMPORTANT Never smoke while working in ...
Symbols
Special coloured labels have been attached near or actually on some of the components
of your Fiat Punto. These labels bear symbols that remind you of the precautions
to be taken as regards that p ...
Engine Oil Filter
The engine oil filter should be replaced with a new filter at every engine oil
change.
Engine Oil Filter Selection
All of this manufacturer’s engines have a full-flow type disposable oil filter.
...