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:
Installation of electric/electronic devices
Electric/electronic devices installed after buying the car or in aftermarket
shall bear the and marking:
Fiat Auto S.p.A. authorizes the installation of transceivers provided that installation
...
Automatic Operation
1. Press the AUTO button on the Automatic Temperature Control (ATC) Panel, the
indicator will illuminate when on.
2. Next, adjust the temperature you would like the system to maintain by adjusting ...
High temperature engine coolant fluid
(red)
Turning the ignition key to MAR the warning light turns on, but it should go
off after few seconds.
The warning light turns on when the engine is overheated.
If the warning light comes on ...