How to Fill a Craftsman 3-Ton Hydraulic Jack

by Tom Goode

Common hydraulic jacks permit lifting the heavy weight of vehicles with relatively low jacking force on the hand-operated handle. Each jack will have a design range, in particular, a minimum and a maximum height. A low hydraulic jack oil reservoir may decrease the maximum available height. The fairly simple procedure of adding oil to the reservoir when necessary can prevent losses in maximum jack height. The process involved in adding oil to the Craftsman 3-ton hydraulic floor jack also applies to many other models.

Step 1

Locate the round fill plug with Phillips-type slots in the top located just forward of the jack handle pivot point and centered side to side. Clean carefully around the plug area to prevent getting dirt into the reservoir when removing the fill plug.

Step 2

Lower the jack completely and use a large Phillips screwdriver to remove the fill plug. Add hydraulic jack oil to bring the oil level to the bottom of the fill hole and replace the plug.

Open the floor jack release valve by turning the jack handle counter-clockwise. Move the jack handle up and down sharply several times to purge any air that may have gotten into the system.


  • Most jacks will have the fill plug located on the cylinder that contains the hydraulic ram. Other possible plug styles include plugs with a hex head or plugs with a hex or a square hole in the top. Remove these types with a. a hex socket, an Allen wrench, or the square end of a ratchet wrench extension bar respectively.
  • Use an old toothbrush or the equivalent and some common spray solvent such as thin lubricant or penetrating oil to clean the area around the fill plug.
  • Use a small funnel to minimize oil spillage and put some old newspapers under the jack when you are working since some oil may get spilled.


  • Hydraulic jack oil is available at auto parts stores. The Craftsman hydraulic jack manual strongly cautions to use only hydraulic jack oil and not to use other type fluids such as power steering fluid or motor oil.
  • Never work under a vehicle supported only by a hydraulic jack. Sometimes hydraulic jacks have slow leaks that cause them to gradually lower under load. Use jack stands or ramps to support the vehicle when you are under it.

Items you will need

  • Cleaning solvent
  • Large Phillips screwdriver
  • Hydraulic jack oil

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