* Your owner's manual: This is the most reliable source.
* The fuel filler door: The sticker on the fuel filler door sometimes lists the tank capacity.
* Your vehicle's identification number (VIN): A VIN decoder (many are available online) can provide details about your truck's specifications, including fuel tank size.
Generally, you'll find fuel tank sizes ranging from 15 to 20 gallons for most S-10 models across different years.