AW32 vs AW46 Hydraulic Oil: What Hydraulic Fluid Should I Use for My Car Lift?

If you are installing a new automotive lift or maintaining an existing one, you may be wondering: What hydraulic fluid should I use for my car lift? Two of the most common hydraulic oils you'll encounter are AW32 and AW46.

The main difference between AW32 vs AW46 hydraulic oil is viscosity, or how thick the fluid is. AW32 is thinner and flows more easily in colder temperatures. AW46 is thicker and may be appropriate for warmer operating conditions or for lifts that specifically require it.

Quick answer: AW32 is commonly used in automotive lifts, particularly in moderate or colder environments. AW46 may be used in warmer environments or when specified by the lift manufacturer. The owner's manual for your specific car lift should always be your final guide.

What Is the Difference Between AW32 and AW46 Hydraulic Oil?

AW stands for Anti-Wear. AW hydraulic oils contain additives designed to help lubricate and protect hydraulic pumps, cylinders, valves and other components in a hydraulic system.

The numbers 32 and 46 refer to the oil's ISO viscosity grade:

• AW32 hydraulic oil is ISO VG 32 and has a lower viscosity.
• AW46 hydraulic oil is ISO VG 46 and has a higher viscosity.

In simple terms, AW32 is thinner and AW46 is thicker.

Temperature matters because hydraulic oil becomes thicker as temperatures fall and thinner as temperatures rise. That's why the operating temperature of your garage or automotive shop can be a factor when a manufacturer allows more than one viscosity.

Should I Use AW32 or AW46 in My Car Lift?

The first thing to check is your car lift owner's or installation manual. If the manufacturer specifies AW32, use AW32. If it specifies AW46, use AW46.

If the manufacturer approves either viscosity, the temperature where the lift operates can help determine which oil is more appropriate.

When AW32 Hydraulic Oil May Be Appropriate

AW32 is thinner than AW46 and generally flows more easily at lower temperatures. This makes AW32 hydraulic fluid for car lifts a common choice in residential garages and automotive shops that experience cooler temperatures.

AW32 may be appropriate when:

• Your car lift manufacturer specifies AW32.
• Your garage gets cold during the winter.
• Your lift is installed in an unheated or partially heated garage.
• Your lift operates in moderate temperatures.
• Your manufacturer allows AW32 for the lift.

When AW46 Hydraulic Oil May Be Appropriate

AW46 has a higher viscosity than AW32. Because hydraulic oil becomes thinner as temperatures rise, AW46 may be appropriate for certain lifts operating in consistently warm environments.

AW46 may be appropriate when:

• Your car lift manufacturer specifies AW46.
• Your shop regularly operates in high temperatures.
• Your lift sees frequent use in a warm commercial environment.
• Your manufacturer specifically approves AW46 for your model.

Important: Don't switch from AW32 to AW46 simply because your shop is warm, and don't switch from AW46 to AW32 simply because your garage gets cold. The manufacturer's approved hydraulic fluid specifications should determine what you put in the lift.

What Hydraulic Fluid Do Different Types of Car Lifts Use?

There is no single hydraulic oil that applies to every automotive lift. Many lifts use AW32 or AW46 anti-wear hydraulic oil, but the exact requirement varies by manufacturer and model.

2-Post Car Lifts

Many 2-post car lifts use AW32 or AW46 hydraulic oil. Because specifications vary between manufacturers, check the manual for your exact model before filling the hydraulic reservoir.

4-Post Car Lifts

Hydraulic 4-post car lifts may also use AW32 or AW46. Larger commercial and alignment lifts can have different hydraulic requirements than smaller residential storage lifts, so always check the manufacturer's specification.

Scissor Car Lifts

Hydraulic car scissor lifts also require manufacturer-specified hydraulic fluid. AW32 and AW46 are commonly encountered viscosity grades, but you should verify the requirement for your specific lift.

If you purchased your lift from HeavyLift Direct and aren't sure which hydraulic oil is required, contact us with the brand and model number and we can help you locate the manufacturer's specifications.

Does a New Car Lift Come With Hydraulic Fluid?

Usually, you should plan on purchasing hydraulic oil separately unless the product listing specifically states that it is included.

Car lifts are often shipped without the hydraulic reservoir filled. The installer adds the proper hydraulic fluid during the installation and setup process.

Before installation day, check your product listing and installation manual to determine:

• Whether hydraulic fluid is included.
• What type of hydraulic fluid the lift requires.
• Whether AW32, AW46 or another fluid is specified.
• Approximately how much hydraulic oil is required.

Having the correct fluid available before your installer arrives can prevent an unnecessary delay during installation.

How Much Hydraulic Fluid Does a Car Lift Need?

There is no universal amount of hydraulic oil required for every car lift.

The amount depends on the size of the hydraulic reservoir, cylinders, hoses and overall lift design. A residential 2-post lift can require a different quantity than a 4-post lift, full-rise scissor lift or heavy-duty commercial vehicle lift.

Use the quantity and filling procedure specified in your lift's installation manual.

Also, don't assume the stated reservoir capacity means you should automatically pour that entire amount into the reservoir. Follow the manufacturer's filling and fluid-level instructions.

When Should Hydraulic Fluid Be Added to a New Car Lift?

Hydraulic oil is normally added during installation and setup, before the lift is placed into normal operation.

The lift should first be assembled according to the manufacturer's instructions. Once the hydraulic power unit, hoses and cylinders are correctly installed and connected, the reservoir can be filled according to the installation manual.

Do not operate a hydraulic power unit without the proper amount of hydraulic oil. Running a hydraulic pump without sufficient fluid can damage the system.

How Do You Add Hydraulic Fluid to a Car Lift?

The exact procedure varies by manufacturer and model, so your installation manual should always take priority. Most automotive lifts use a hydraulic power unit with an attached reservoir.

A typical installation process may include:

1. Complete the lift installation. Install the hydraulic power unit, hoses and cylinders according to the manufacturer's instructions.
2. Inspect the hydraulic connections. Make sure fittings and hoses are properly connected.
3. Locate the hydraulic reservoir. It is typically attached to the lift's hydraulic power unit.
4. Locate the fill port or breather cap. Follow the manufacturer's instructions for opening the reservoir.
5. Add the specified hydraulic oil. Use the exact type and viscosity required for the lift.
6. Avoid overfilling. Add the amount recommended by the manufacturer.
7. Cycle the lift according to the startup procedure. This allows hydraulic oil to move through the hoses and cylinders.
8. Inspect for leaks. Check the hoses, fittings, cylinders and power unit.
9. Recheck the fluid level. Follow the manufacturer's procedure for checking the final reservoir level.

Never work underneath a lift during installation or hydraulic testing unless the lift is properly supported and all manufacturer safety procedures are being followed.

Where Can I Buy AW32 or AW46 Hydraulic Oil?

AW32 and AW46 hydraulic oil are widely available. You can typically find them at:

• Automotive parts stores
• Farm and tractor supply stores
• Industrial supply companies
• Hydraulic equipment suppliers
• Hardware and home improvement stores
• Online retailers

When purchasing hydraulic oil, check the container carefully to make sure you're buying the viscosity specified by your lift manufacturer.

You generally don't need hydraulic oil carrying the same brand name as your car lift unless the manufacturer specifically requires a particular product. The important factor is meeting the fluid type, viscosity and other specifications required for your lift.

Can You Substitute AW32 and AW46 Hydraulic Oil?

You should not automatically substitute AW46 for AW32 or AW32 for AW46.

AW46 is thicker than AW32, so substituting it for AW32 can affect hydraulic operation, particularly at lower temperatures. Likewise, AW32 is thinner and should not automatically replace AW46 in a system designed for the higher viscosity.

If your car lift manufacturer permits both AW32 and AW46, operating temperature may help determine which one to use. If the manufacturer specifies only one viscosity, use that viscosity unless the manufacturer tells you otherwise.

Can You Mix AW32 and AW46 Hydraulic Oil?

As a general maintenance practice, avoid unnecessarily mixing hydraulic oils.

If you are topping off the reservoir, use the same viscosity and type recommended for the lift. Different hydraulic oil brands may also contain different additive packages.

If you don't know what fluid is currently in your car lift, check your maintenance records or owner's manual before adding more oil.

Why Does Hydraulic Oil Viscosity Matter?

A car lift's hydraulic pump moves fluid under pressure to operate the hydraulic cylinders. The viscosity of the oil affects how easily that fluid moves through the system.

Hydraulic oil that is too thick for the operating conditions may contribute to slower operation, particularly when the garage is cold. Oil that is too thin may not provide the viscosity intended by the lift manufacturer.

Using the correct car lift hydraulic oil helps the hydraulic system operate as the manufacturer intended.

AW32 vs AW46 in Cold and Hot Garages

Cold or Unheated Garages

If you have a car lift in an unheated garage and the manufacturer allows AW32, AW32 will generally flow more easily than AW46 at colder temperatures.

This can be particularly relevant for homeowners and shops in northern climates where garage temperatures can drop considerably during winter.

Hot Garages and Commercial Shops

AW46 has a higher viscosity than AW32 and may be appropriate for certain lifts operating in hotter environments because hydraulic oils naturally become thinner as their temperature increases.

However, temperature alone shouldn't determine your hydraulic fluid. A hot garage doesn't automatically mean you should use AW46, just as a cold garage doesn't automatically mean you should use AW32. The viscosity must be approved for your specific lift.

AW32 vs AW46 for Car Lifts: The Bottom Line

When comparing AW32 vs AW46 hydraulic oil for a car lift, the biggest difference is viscosity:

• AW32 is thinner and generally flows more easily in colder temperatures.
• AW46 is thicker and may be appropriate for certain lifts operating in warmer conditions.
• The manufacturer's specification should ultimately determine which hydraulic fluid you use.

If you're installing a new lift, check the hydraulic fluid requirement before installation day. In many cases, the hydraulic oil must be purchased separately and added during installation.

If you're still shopping for a lift, browse HeavyLift Direct's selection of car lifts for garages and automotive shops, including 2-post lifts, 4-post lifts, scissor lifts and portable car lifts.

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Frequently Asked Questions About Car Lift Hydraulic Fluid

Is AW32 hydraulic oil the same as ISO 32?

AW32 is an anti-wear hydraulic oil with an ISO viscosity grade of 32, commonly referred to as ISO VG 32. Check your lift manual for any additional hydraulic fluid requirements beyond viscosity.

Is AW46 hydraulic oil the same as ISO 46?

AW46 is an anti-wear hydraulic oil with an ISO viscosity grade of 46, or ISO VG 46. It has a higher viscosity than AW32.

Can I use automatic transmission fluid in a car lift?

Only use automatic transmission fluid if the manufacturer of your specific car lift lists it as an approved fluid. Don't substitute ATF for AW32 or AW46 simply because it is available.

Can I use tractor hydraulic fluid in a car lift?

Only use tractor hydraulic fluid if your car lift manufacturer specifically approves it. Tractor hydraulic fluids can have different viscosity characteristics and additive packages than the hydraulic oils specified for automotive lifts.

What happens if I put the wrong hydraulic oil in my car lift?

Using an incorrect viscosity can affect how the hydraulic system operates. Fluid that is too thick can contribute to slower operation, particularly in cold temperatures, while fluid that is too thin may not provide the viscosity intended for the system. If you believe the wrong fluid has been added, consult the lift manufacturer before continuing to operate the equipment.

Why does my car lift move slower when it's cold?

Hydraulic oil becomes thicker as its temperature decreases. This increased viscosity can make a hydraulic lift operate more slowly until the fluid and surrounding environment warm up. If your manufacturer approves AW32, its lower viscosity can provide easier flow at colder temperatures than AW46.

How do I know if my car lift is low on hydraulic fluid?

Check the hydraulic reservoir according to the procedure in your owner's manual. If the fluid level has dropped, inspect the hydraulic system for visible leaks rather than simply continuing to add oil.

Should my car lift be raised or lowered when checking the hydraulic fluid?

This depends on the design of the lift. Cylinder position affects how much hydraulic oil is in the reservoir, so checking the level with the lift in the wrong position can give an inaccurate reading. Follow the manufacturer's procedure for your specific model.

How often should I check the hydraulic fluid in my car lift?

Hydraulic fluid should be inspected according to the maintenance schedule provided by the lift manufacturer. You should also inspect the system if you notice a leak or a change in how the lift operates.

How often should car lift hydraulic fluid be changed?

There isn't one replacement interval that applies to every automotive lift. Follow the maintenance schedule specified by your lift manufacturer for the correct inspection and fluid-change intervals.

Can I top off my car lift hydraulic fluid?

Yes, when necessary, but use the same type and viscosity of hydraulic fluid specified for your lift. If the fluid level continues to drop, inspect the hydraulic system for a leak.

Does the brand of AW32 or AW46 hydraulic oil matter?

The most important consideration is whether the hydraulic oil meets the specifications required by the lift manufacturer. Check the owner's manual for any required fluid standards or restrictions before purchasing hydraulic oil.

How much AW32 or AW46 should I buy before installing my lift?

Check the installation manual for your exact lift before purchasing hydraulic oil. Different 2-post, 4-post, scissor and heavy-duty lifts can require different amounts. Buying the manufacturer's recommended quantity before installation can help prevent delays.

Need Help Choosing or Installing a Car Lift?

HeavyLift Direct carries automotive lifts for home garages, repair shops, dealerships, fleets and professional automotive facilities. If you aren't sure which lift or hydraulic fluid specification applies to your application, contact us with the lift's brand and model number and we'll help point you in the right direction.

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