Ford Mercury Villager 1997 Owner's Manual page 338

Engine
Start the engine every 15 days. Run it at fast idle until it
reaches normal operating temperature.
With your foot on the brake, shift the transaxle into all gears
while the engine is running.
Fuel system
Fill fuel tank with high-quality unleaded fuel until the first
automatic shutoff of the fuel pump nozzle.
NOTE: During extended periods of vehicle storage (60 days or
more), fuel may deteriorate due to oxidation. This can
damage rubber and other polymers in the fuel system
and may also clog small orifices.
Ford Gas Stabilizer should be added whenever actual or expected
storage periods exceed 60 days. Follow the instructions on the
label. The vehicle should then be operated at idle speed to circulate
the additive throughout the fuel system.
A volatile corrosion inhibitor added to the fuel system will
protect the fuel system's inner surfaces from corrosion. Follow
the instructions packaged with the product.
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