How to Fill A Bottle Jack with Oil in DIY

All kinds of hydraulic jacks are important for their technical functions, but when it comes to vehicles specifically, bottle jacks are the best choice. With their versatile uses and easy-to-carry structure.

A bottle jack is one of the types of hydraulic jacks, that is mounted in a vertical fashion underneath the load. The bottle jacks are designed in such a way that lifting heavy loads such as pickup trucks becomes easier.

Due to their narrow frame, compact size, and smooth lifting mechanism, bottle jacks are considered highly efficient.

Bottle jacks need appropriate maintenance and care for their optimum performance and smooth lifting action. For which experts suggest that you regularly add oil in a jack so that the friction between the pump can be minimized.

As oil is the most significant component in a bottle jack, it is important to learn the right way of doing it.

8 Steps To Fill A Bottle Jack With Oil 

Before beginning the process of how to fill a bottle jack with oil, make sure you have all of these tools with you, and follow these steps carefully.

Tools Needed

  • Screwdrivers
  • Squeeze bottle
  • Extra rags
  • Paper towels or newspaper
  • Hydraulic jack oil

Step 1: Put the bottle jack on an even spot 

The first thing you need to do is to place the bottle jack on flat ground, preferably an even spot like a table or your workstation.

This prevents the chances of the jack tilting over or falling down while you are pouring the oil. The oil spillage from the chamber during the process is also reduced when the jack is on a flat horizontal spot.

Step 2: Spread a rag or newspaper under your jack

During the oil filling process, there is a fair chance that some oil might leak while you are pouring it. To keep the surface clean from oil, it is best to place a newspaper or an extra rag under the bottle jack.

The rag absorbs all the leaking oil and you are exempted from the mess of cleaning up later on.

Step 3: Find the oil filler plug

Once you have settled the bottle jack in a perfect position, look out for the oil filler on its top side. The oil filler has a tiny rubber cap that prevents the oil from coming out of the jack while in use.

Step 4: Open the plug with a screwdriver 

Take a screwdriver that has a flat tip and slowly take out the tiny rubber oil filler. The rubber filler plug is fitted very tightly in the hole, therefore it cannot be taken out with your fingers.

Make sure to put it out carefully and slowly so that the leftover oil from inside the cylinder doesn't spurt out at you.

Step 5: Put the hydraulic oil in the bottle squeezer

Since the oil filler opening is really tiny, you cannot pour the oil directly into it without spilling most of it. That’s why a plastic bottle squeezer is used, with an extended and pointed tip.

Put enough oil in the plastic bottle and then move on to the next step.

Step 6: Pour the oil into the filler 

This step is the precise answer of how do you fill the bottle jack. Point the tip of the plastic bottle into the oil filler and slowly start squeezing the bottle. Do it until the whole cylinder is filled with oil, do not over or underfill the reservoir.

Ensure that the tip of the bottle is inside of the filler all this time otherwise the oil might leak out. The best way of knowing when you should stop pouring is by checking the oil levels under the filler opening.

According to experts, don’t add more oil when the oil reaches 0.3 cm below the oil hole.

Step 7: Place the filler plug back in place

When you are done with pouring the oil in the filler opening, take out the tip of the bottle and place the plug back in its place.

Never lose that tiny rubber plug because if it’s gone there is not much use for filling the oil in the first place. Try to take it out with your fingers afterward to make sure it is fitted tightly in its place.

Step 8: Rub the excess hydraulic oil with a cloth

The area underneath the bottle jack might be covered with rags to seep the oil spills but there is always a bit of oil left outside the filler plug. Take a cloth and wipe away the spilling oil around the filler opening and the plug.

Doing this is necessary after every oil refill, to avoid the exterior of your bottle jack from getting slippery and causing accidents.

How A Hydraulic Bottle Jack Works?

A bottle jack works using the hydraulic oil that goes inside of it, the idea of this type of pump was first introduced by Blaise Pascal. A hydraulic bottle jack operates on Pascal’s principle which states that in a walled container, a pressure change in any one part will bring a change in every part.

The bottle jack works when you put it underneath your truck or any other load and push the handle. Lifting the handle allows the hydraulic oil to be moved to a smaller piston, which in return applies pressure on a larger piston.

As much as you push the handle, more pressure will be applied to the larger piston due to the liquid present in the bottle pump.

The build-up pressure in the piston gives the cylinder of the bottle jack a push which keeps heavy loads stable, for as much time as needed.

The oil in the bottle jack provides all the power to the piston to move up, which eventually lifts heavy loads to different heights. Continuous pushing of the handle adds more pressure to the cylinder and lifts the heavy load higher.

For lowering your truck or whatever cargo you have lifted to its normal position, there is a valve that reverses the pressure produced by the hydraulic oil.

When you turn the handle back down, the valve releases the hydraulic fluid back to its original reservoir. The pressure in the cylinder and the pistons normalizes and the load moves down.

What Kind Of Oil Goes In A Bottle Jack?

You should have idea about what kind of oil goes into a hydraulic bottle jack. Typically, the bottle jacks use synthetic or mineral based hydraulic oil which is different than the motor oil you put in your cars.

To provide enough power and stability to be the cylinder of the jack, the hydraulic oil is the best, since it is of low viscosity.

Another significant property of hydraulic oil is that it is a non-compressible fluid, making it ideal for instruments working on Pascal’s principle.

Mechanical experts emphasize not putting any motor oil or brake oil in your hydraulic bottle jack if you run out of hydraulic fluid. The reason behind this is the higher alcohol contents in the brake fluids that can be risky for your hydraulic machine.

However, you can use some of the lightweight motor oils as a temporary solution for your jack.


1. What is a bottle jack oil fill plug?

The bottle jack oil fill plug is a tiny rubber cap that closes the oil filler hole and prevents oil leaks after you have filled the jack with oil. The rubber composition of the oil filler plug keeps the oil from spilling with its tight-fitting.

2. How do you check the oil in a bottle jack?

You can check the oil levels in the bottle jack by opening the tiny oil filler plug and seeing the oil below the hole. If you notice that your hydraulic bottle jack is not working at full efficiency it is another signal to fill your jack with oil.

3. Can you use the motor oil in a bottle jack?

No, using motor oil for the hydraulic bottle jack is not a good idea at all, due to the viscosity and the temperature of the motor oil. Similarly, never add any brake fluid to the jack due to the high alcohol contents in it.

4. How do you get the air out of a hydraulic jack?

To get the air out of the hydraulic jack, open the valve to release the pressure, by depressing the handle of the jack for a couple of seconds. In the bottle jack, you can release the pressure by lowering the handle on the side.

5. How much oil goes in a bottle jack?

There is no exact measurement of how much oil you should put in a bottle jack since they come in a variety of sizes. But a rule of thumb is that stop adding oil when the oil reaches 0.3 cm lower the filler hole.

You can also stop pouring more oil when the oil starts coming out of the hole.

6. How do you make a hydraulic bottle jack go down?

To take the bottle jack back to its original position, use the side handle. Lower the handle so that the pressure is released through the valve.

Keep lowering the handle to release all of the air and the pressure from the jack and the cylinder will go down to its initial position.

Final Verdict

A hydraulic bottle jack cannot function without its core component, and the driving force behind it; the hydraulic oil. Without the oil or any fluid in the bottle jack, there would not be any pressure formation to provide power for lifting the heavy loads.

When you use a bottle jack for some time, the oil from the pistons leaks a little bit, and eventually, you have to refill the cylinder with more oil.

That is why understanding the process of filling a bottle jack with hydraulic oil is a must for anyone that owns a bottle jack. It can also save a person from getting into messy accidents while using the bottle jack.

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