All gasoline sold in the United States is required to contain effective detergent additives. Use of additional detergents or other additives is not needed under normal conditions and would result in additional cost. Therefore you should not have to add anything to the fuel.
See also:
Brake System
In order to assure brake system performance, all brake system components should
be inspected periodically.
Refer to the “Maintenance Schedule” for the proper maintenance intervals.
WARNING!
Ridi ...
Diesel fuel filter sensor failure
The warning light on the dial comes on (on certain versions together with the
message on the display) when dieel fuel filter sensor failure is detected. Contact
Fiat Dealership as soon as poss ...
Transmission
CLUTCH
Hydraulic, self-adjusting external control.
GEARBOX
Five forward gears and reverse with synchromesh for front gear engagement.
Cyclical gear reduction and differential assembly incorporated ...