What Hydraulic Fluid Does a Car Lift Use? AW32 vs AW46

Short answer: almost every hydraulic car lift runs on anti-wear hydraulic oil, and the two grades you'll see called out are AW32 and AW46. AW32 is the thinner of the two and the default for most home garages and moderate climates. AW46 is a touch thicker and the better pick for hot shops, hard daily cycling, or warm-weather states where a thin oil thins out even further. Both are the same basic chemistry, so you're choosing viscosity, not a whole different product.

Here's the part most spec sheets bury: your lift's manual is the tie-breaker. Some manufacturers print "AW32," some print "AW46," and plenty print "AW32 or Dexron ATF" and mean it. Below we'll walk through what the AW label actually means, how to choose between 32 and 46 for your garage, what your fluid holds and how to fill it, and the fluids you should never pour into a lift power unit. If you keep the right oil in it and check the level once in a while, a lift's hydraulic system will outlast the rest of the garage. 

The Short Answer: AW32 vs AW46

Rule of thumb: if your garage lives in a normal temperature range and you lift a few cars a week, AW32 is the safe default and what most lift makers ship their units expecting. If your lift works in a hot climate, runs all day in a busy shop, or sits in a space that swings well past 90°F in summer, AW46 holds a stronger oil film when everything heats up.

The reason comes down to one fact about oil: it gets thinner as it gets hotter. A grade that feels perfect at 70°F can thin down enough at 110°F that the pump loses efficiency and the seals see more wear. Picking the slightly heavier AW46 in a hot environment keeps the fluid in its happy range. In a cold, unheated garage the opposite is true, and the thinner AW32 (or an even lighter grade if the manual allows it) moves better on a freezing morning. Match the oil to the temperature the lift actually works in, not the season you're standing in when you buy it.

If you only remember one thing: pull the manual, read the fill spec, and buy exactly that. When the manual gives you a choice, use the climate rule above to break the tie.

What "AW" and the Numbers Actually Mean

"AW" stands for anti-wear. It's a family of hydraulic oils built on a refined mineral base with a specific additive package. The additives are what make it right for a lift instead of just any oil lying around:

• Anti-wear additives (usually a zinc compound, ZDDP) that protect the pump gears and cylinder walls under high pressure.
• Rust and corrosion inhibitors that protect the steel inside the reservoir, cylinders, and lines.
• Anti-foam agents so the pump moves solid oil, not a churned-up mix of oil and air.
• Demulsifiers that force water to separate and drop to the bottom instead of staying suspended in the oil. That's a big deal, and it's exactly the opposite of what motor oil is designed to do.
• Oxidation stabilizers that keep the oil from turning to sludge over years of service.

The number after "AW" is the ISO viscosity grade (ISO VG). It's a measure of how thick the oil is at 40°C (104°F), stated in centistokes. AW32 measures right around 32 centistokes at that temperature; AW46 measures around 46. Higher number, thicker oil. You'll also see AW22 (thinner, for very cold service) and AW68 (thicker, for heavy industrial use), but on automotive lifts the conversation lives almost entirely between 32 and 46.

One more label you'll run into: some lifts, especially older or imported ones, spec Dexron automatic transmission fluid instead of, or alongside, AW oil. ATF behaves like a light hydraulic oil with a slightly different additive set, and manufacturers that approve it usually list it right next to AW32. If your manual says ATF is acceptable, it is. If it doesn't mention ATF, stick with the AW grade it prints.

AW32 vs AW46: Which One Does Your Lift Need?

Since the two grades are the same chemistry at different thicknesses, they're fully compatible and you won't damage anything by choosing "wrong." What you'll notice is performance at the edges of the temperature range. Here's how to decide:

Reach for AW32 when:

• Your garage stays in a normal range, roughly 40°F to 90°F through the working day.
• You're a home user lifting a handful of vehicles a week, not running full duty cycles.
• You live in a cold climate and want the lift to move smoothly on winter mornings.
• The manual lists AW32 first or lists it as the only spec.

Reach for AW46 when:

• The lift works in a hot climate or an un-air-conditioned shop that bakes in summer.
• You're cycling the lift hard all day and the power unit gets warm to the touch.
• You want a little more film strength under sustained heavy loads near the lift's rated capacity.
• The manual specs AW46, which some higher-capacity and commercial lifts do.

Can you mix them? Yes, in a pinch. Because both are anti-wear oils on the same base, topping off an AW32 system with a bit of AW46 (or vice versa) won't hurt anything. You'll just end up with a blended viscosity somewhere in between. For a full fill, though, pick one grade and stick with it so the system behaves predictably. This flexibility is one reason hydraulic lifts are so low-maintenance compared to the air-over-hydraulic scissor lifts → that add a compressor into the mix.

What Your Specific Lift Uses

The single most reliable source is the fill plate on the power unit or the maintenance page of your owner's manual. That said, here's the pattern across the brands we sell and service most, so you know what "normal" looks like:

Katool →. The volume two-post and four-post lifts run on standard AW32 hydraulic oil. It's the easy-to-find, inexpensive grade, which keeps ownership cost low. Our 2-post car lift → customers on Katool almost never have to hunt for special fluid.

AMGO. Most AMGO two-post and four-post units spec AW32, with AW46 acceptable in hot climates. AMGO also lists Dexron ATF as an approved alternative on several models, which is handy if that's what your parts store has on the shelf.

Tuxedo →, Triumph →, and Atlas →. These generally follow the same script: AW32 as the baseline, AW46 for warm-climate or heavy-duty service. Always confirm on the specific model's plate, because capacities and grades vary between a 9,000 lb two-post and an 11,000 lb four-post.

If you bought your lift used and the manual is long gone, AW32 is the statistically safe choice for a home two-post or four-post in a temperate climate. But before you commit to a full fill, it's worth a two-minute call. Our Lift Specialists can look up the exact fill spec for most makes and models we carry.

Substitutes and What You Should Never Use

When you're mid-project and the reservoir is low, the temptation is to grab whatever's on the shelf. Some substitutes are fine. Several will quietly wreck your seals and pump. Know the difference.

Acceptable when the manual allows it:

• Dexron ATF (Dexron III / Mercon), but only if your manufacturer lists it. Many import and older lifts are perfectly happy on ATF.
• A different AW grade than specced, in a pinch, understanding you're shifting viscosity as described above.

Hard no's, never pour these into a lift:

• Motor oil. This is the most common mistake. Engine oil is loaded with detergents that hold water and contaminants in suspension, exactly the opposite of what a hydraulic system needs. It also foams more readily. It'll run for a while, then cost you seals.
• Brake fluid. Glycol-based, aggressively absorbs water, and it's incompatible with hydraulic lift seals. It will swell and destroy them.
• Power steering fluid. Not formulated for the pressures or the seal materials in a lift, despite looking similar to ATF.
• Old, milky, or contaminated oil drained from anything. Milky means water is already emulsified in it, and you'd be pouring in the problem you're trying to avoid.

The theme is water. A proper AW oil sheds water so it can settle out and be drained. Motor oil and brake fluid trap it, and trapped water is what rusts cylinders and pits pump parts. Spend the fifteen dollars on the right oil.

How Much Fluid a Lift Holds and How to Fill It

Capacity is smaller than people expect. A typical two-post lift power unit holds roughly 2.5 to 3 gallons (about 10 to 12 quarts). A four-post is often similar, sometimes a bit more because of the longer lines and the cylinder size. A single one- or two-gallon jug of AW32 covers most home fills, but buy the size your manual calls for and keep a little extra for top-offs.

Filling it right matters as much as the fluid itself. The golden rule: fill with the lift fully lowered. If you fill while the carriage is up, the oil that's currently out in the cylinders will come back to the reservoir when you lower the lift and overflow it. Here's the clean sequence:

• Lower the lift all the way down so the cylinders are retracted and their oil is back in the tank.
• Pull the fill plug or cap on the power unit and add AW oil to the marked level (or the "full" line on the dipstick if it has one).
• Raise and lower the lift through its full travel two or three times with no vehicle on it. This purges trapped air out of the cylinders and lines.
• Lower it fully again and re-check the level. Air pockets will have worked out, so you'll usually need to top it off a little.
• Repeat until the level holds steady after a full cycle.

Trapped air is the usual culprit behind a lift that rises in jerky steps or feels spongy on the way up. Bleeding it out with a few empty cycles fixes most of that. If your lift uses equalizer or slack-safety cables, check them at the same time; on a well-maintained lift the cables work in tension within their rated limits, with substantial safety factors built in, and the mechanical safety locks catch any failure regardless.

Changing and Checking Your Hydraulic Fluid

Hydraulic oil in a lift lives an easy life compared to engine oil. It doesn't see combustion byproducts, and a closed system stays clean if it's sealed well. Most lift makers suggest changing the fluid every one to two years for a busy shop, and longer intervals are common for lightly used home lifts. The more useful habit is checking the level and condition monthly and topping off as needed.

What you're looking for when you check:

• Level. With the lift fully lowered, it should sit at the fill mark. A dropping level over time points to a small leak worth chasing down.
• Color and clarity. Fresh AW oil is clear to light amber. Dark, cloudy, or milky oil means it's oxidized or has taken on water and should be changed.
• Foam. A frothy surface means air is getting drawn in, often from a low level or a loose fitting.

To change it, lower the lift completely, drain the reservoir (some units have a drain plug, others you siphon or pump out), refill with fresh AW oil to the mark, then cycle and bleed as described above. It's a fifteen-minute job that protects a multi-thousand-dollar machine. For the full rundown of what to check and when, our lift maintenance checklist lays out the daily, monthly, and yearly items in one place.

Fluid-Related Problems and Fixes

Most "the lift is acting up" complaints trace back to fluid level, air, or contamination before anything mechanical. Start here:

Lift rises slowly or won't reach full height

Usually a low fluid level. Check it with the lift down and top off. If the level is fine, the pump may be worn or a suction filter clogged, but check the cheap and easy cause first.

Lift rises in jerky steps or feels spongy

Air trapped in the cylinders and lines. Run the empty lift up and down through full travel a few times to bleed it, then re-check the level. This is the single most common post-install complaint and it's almost always just air.

Oil looks milky or cloudy

Water contamination. AW oil is designed to shed water, but if enough gets in, it emulsifies. Drain and refill with fresh oil, and figure out where the water came in (a vented cap in a humid space is a common path).

Lift slowly settles or creeps down overnight

This one is usually not the fluid grade. It points to a leaking cylinder seal or a check valve not seating, letting oil bleed back. This is why you always rest a loaded lift on its mechanical safety locks, never on hydraulic pressure alone. If a lift won't hold on its locks, stop using it and get it serviced. For a broader walk-through of hydraulic, electrical, and structural gremlins, see our common lift problems guide.

Frequently Asked Questions

Can I use AW46 instead of AW32 in my car lift?

Yes. They're the same anti-wear hydraulic oil chemistry at different viscosities, so they're compatible. AW46 is slightly thicker, which helps in hot conditions but can make the lift feel a little slower in the cold. If your manual specs AW32 and you're in a moderate or cold climate, AW32 is the better match, but AW46 won't harm the system.

Is hydraulic jack oil the same as AW32?

Often, yes. Many products sold as "hydraulic jack oil" are ISO 32 anti-wear oils under a different label. Check the container for the ISO viscosity grade and an AW or anti-wear designation. If it says ISO 32 and lists anti-wear additives, it's functionally AW32.

Can I use transmission fluid (ATF) in my lift?

Only if your lift's manufacturer approves it. Many older and imported lifts list Dexron ATF as an acceptable fluid right alongside AW32. If your manual doesn't mention ATF, use the AW grade it specifies instead.

How much hydraulic fluid does a two-post lift take?

Most two-post lift power units hold roughly 2.5 to 3 gallons, about 10 to 12 quarts. Four-post lifts are often similar. Always fill to the manufacturer's mark with the lift fully lowered, then cycle and re-check.

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

A busy shop should plan on every one to two years; a lightly used home lift can go longer. More important than the calendar is checking the level and condition monthly and topping off or changing it if the oil turns dark, cloudy, or milky.

Why does my lift jerk or rise unevenly after I add fluid?

Trapped air. After filling, raise and lower the empty lift through its full travel two or three times to bleed the air out of the cylinders and lines, then re-check and top off the level with the lift down.

Our Top Picks

Here are the standouts from this category, picked by our Lift Specialists for real-world fit and value.

Katool KT-H105: 10,000 lb 2-Post (Budget Pick)

💳 Affirm & Shop Pay Installments at checkout | $1,899

Katool's volume two-post and the strongest entry-tier value in the category. Dual-cylinder hydraulic, 10,000 lb capacity, symmetric design. Runs on standard AW32 hydraulic oil, so fluid is easy to find and inexpensive.

Best for: Budget-focused buyers who still want 10K capacity and basic safety features.

View Pricing & Specs →

★★★★★ Verified reviews · Authorized dealer · Lift Specialists ready to help

AMGO BP-9: 9,000 lb 2-Post (Mid-Tier Pick)

💳 Affirm & Shop Pay Installments at checkout | $2,335

A solid mid-tier baseplate two-post with a single-point safety release and 9,000 lb capacity. Best-selling AMGO two-post for home garages and light shops, with an easy-maintenance hydraulic system.

Best for: Home garages with 11-foot-plus ceilings looking for a step up from import budget brands.

View Pricing & Specs →

★★★★★ Verified reviews · Authorized dealer · Lift Specialists ready to help

Katool KT-4H110: 11,000 lb 4-Post (Storage & Service Pick)

💳 Affirm & Shop Pay Installments at checkout | $3,299

An 11,000 lb four-post that doubles as a storage lift and a service platform. Bigger fluid capacity than a two-post, but the same simple anti-wear-oil maintenance story.

Best for: Owners who want storage plus service capability in one lift.

View Pricing & Specs →

★★★★★ Verified reviews · Authorized dealer · Lift Specialists ready to help

Take the Next Step

Hydraulic fluid is the easiest part of lift ownership to get right: buy the AW grade your manual specs, keep the level topped off with the lift down, and change it when it turns cloudy. Do that, and the power unit becomes the part of your lift you almost never think about. AW32 covers the vast majority of home garages; AW46 is the smart move for hot shops and hard daily cycling.

If you're still shopping for the lift itself and want one with a simple, low-fuss hydraulic system that runs on easy-to-find oil, that's exactly what our Lift Specialists help people sort out every day. Tell us your ceiling height, your slab, and the vehicles you service, and we'll point you at the right setup. Call or text (470) 208-2754 or browse the full vehicle lifts collection → to see what's in stock.

Keep Reading

External authority: ALI Directory of Certified Lifts (auto-lifts.org) · OSHA 1910.178 (Workplace lift safety regs)