Honda Civic Service Manual: Engine Cooling

Engine

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Coolant Replacement (R18A9)

1. Radiator Cap 1. Wait until the engine is cool, then carefully remove the radiator cap. ...

See also:

Honda Civic Owners Manual. Changing a Flat Tire
If a tire goes flat while driving, grasp the steering wheel firmly, and brake gradually to reduce speed. Then, stop in a safe place. Replace the flat tire with a compact spare tire. Go to a dealer as soon as possible to have the full-size tire repaired or replaced.  Park the vehicl ...