What can you substitute for hydraulic oil in a floor jack?

When it comes to maintaining your floor jack’s performance, finding a suitable substitute for hydraulic oil can be essential in a pinch. Whether you’ve run out of hydraulic oil or want an alternative for environmental reasons, it’s crucial to know your options. In this article, we’ll explore various substitutes and their pros and cons, helping you make an informed decision to keep your floor jack in top shape without compromising safety or functionality.

Here’s a quick answer: While hydraulic jacks are designed for specific hydraulic oils, in an emergency automatic transmission fluid, motor oil, or brake fluid can temporarily substitute. However, this can reduce performance and damage components, so manufacturer recommended hydraulic oil should be used as soon as possible. Always check equipment manuals before substituting.

Hydraulic jacks are designed and manufactured to use a specific weight and grade of hydraulic oil for optimal performance. Hydraulic oil has properties that:

  • Allow smooth operation of the internal mechanisms
  • Protect metal components from wear and corrosion
  • Maintain proper viscosity at a range of temperatures
  • Resist break down from compression

The vehicle manufacturer or floor jack manufacturer specifies the recommended type of hydraulic oil to use in the equipment’s owner’s manual. Using the recommended oil ensures the jack will have:

  • Maximum lifting capacity
  • Consistent lifting speed
  • Minimal internal wear and leakage
  • Long service life

Using an improper fluid can reduce lifting performance and damage the jack’s seals, valves, and cylinders over time.

Potential substitute fluids

If recommended hydraulic oil is not available, some potential substitute fluids include:

Transmission fluid

Automatic transmission fluid (ATF) is a common substitute because it has some similar properties to hydraulic oil. Make sure to use a dexron or import multi-vehicle ATF. Benefits include:

  • Good viscosity index to work at hot and cold temps
  • Anti-wear agents to protect internal parts
  • Age resistance for long fluid life

However, ATF may have less lubricating capability and improper additives compared to hydraulic oil.

Motor oil

Standard motor oils like 10W or straight 30 weight oil can also work as an emergency hydraulic fluid substitute. They have adequate viscosity ratings to transmit hydraulic power. However, they are not formulated for the high pressures inside a hydraulic jack system. Motor oils also lack corrosion protection.

Brake fluid

DOT 3 or DOT 4 brake fluid is sometimes used as a hydraulic jack fluid substitute because it is hydraulic-based. However, brake fluid is designed for much lower pressures and temperatures. It can aerate easily and cause damage to seals and o-rings. Brake fluid also absorbs moisture which can cause corrosion.

Other oil substitutes

Light lubricating oils, mineral oils, vegetable oils, transmission stop-leak additives, methanol, and alcohol may work, but are not recommended. They do not have the ideal properties for hydraulic applications, and can cause operational issues or equipment damage.

Considerations when using a substitute fluid:

  • Check manufacturer recommendations – The vehicle or equipment manual will specify if an alternative fluid can be safely used.
  • Use sparingly and replace – Substitute fluid should only be used on a very limited basis until the proper hydraulic oil can be obtained. The system should be flushed to replace the substitute fluid with the recommended oil as soon as possible.
  • Inspect regularly – When using an alternative fluid, inspect the jack more frequently for any signs of leaking, abnormal operation, or damaged seals. Discontinue use if issues arise.
  • Lower capacities expected – Substitute fluids will likely reduce the lifting capacity of the jack somewhat. Avoid lifting to full rated capacity.
  • Filter the fluid – Any contaminants or particles can easily damage hydraulic system components. Always try to use filtered fluid.

FAQ about hydraulic jack fluid substitutes

Is it safe to use other types of oil in my hydraulic jack?

It is not recommended because most other oils lack the specific properties needed for hydraulic jacks to operate properly and safely. Using the wrong fluid can damage the jack. Always follow manufacturer specifications.

Can I use old hydraulic fluid if I don’t have enough new fluid?

No, old hydraulic fluid that has been contaminated should not be used. It likely contains metal shavings or varnish that can block valves and damage the system. Always replace with new, clean oil.

How much should I lower my jack’s weight capacity if I have to use a substitute fluid?

It’s best to reduce the lifting capacity by at least 20-30% as a safety precaution if using a temporary replacement fluid other than the manufacturer recommendation.

Do I need to bleed the system if I top it off with an alternative fluid?

Yes, thoroughly bleed and flush the hydraulic system after using a substitute, and replace any filters or strainers. This removes any contaminants and replaces the temporary fill fluid with the proper hydraulic oil.

Can I mix different types of oil together in my hydraulic jack?

No, never mix different types of hydraulic oils or other fluid types. This can cause chemical reactions, fluid breakdown, and serious operating issues.

How often should I inspect my jack if using an alternative temporary fluid?

Check for leaks and abnormal operation every few uses until you can replace the fill with the intended hydraulic oil. Damage can occur rapidly with improper fluids.


Hydraulic floor jacks require specialized hydraulic oil to lift heavy loads safely. Substitute fluids like transmission fluid or motor oil can work temporarily in an emergency, but performance is compromised. Always use manufacturer recommended hydraulic oil if possible, and replace substitute fill fluid as soon as feasible.

Proper care maximizes the jack’s lifting capability and service life. Check the equipment manual for oil specifications, capacities, maintenance tips, and warnings when using alternative temporary fluids.


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