CAT Hydraulic Oil: Which Type Your Machine Needs

The standard Cat hydraulic oil is HYDO Advanced 10, an SAE 10W oil that Caterpillar uses as the typical factory fill and rates for -4°F to 104°F. Hotter work calls for HYDO Advanced 20 or 30. Cat also lists its own engine and drivetrain oils as backups, and does not recommend industrial AW hydraulic oils at all.

Key Points

• Factory fill: HYDO Advanced 10 (SAE 10W), rated for -4°F to 104°F. Machines built for biodegradable oil leave the factory with Bio HYDO Advanced instead.
• Hot climates: HYDO Advanced 20 (23°F to 113°F) or HYDO Advanced 30 (up to 122°F). Cat picks the grade by the coldest temperature you start and work in.
• Skid steers: the loader hydraulics and the hydrostatic drive run on the oil in one hydraulic tank. The drive chain cases are separate and take engine oil, not hydraulic oil.
• Alternatives: Cat's own MTO, DEO and TDTO oils first, then commercial oils that meet Cat ECF or TO-4 specs and carry at least 900 ppm zinc. Industrial hydraulic oils are not recommended.
• Change interval: up to 3,000 hours with HYDO Advanced 10 on D-series loaders, or 6,000 hours with S·O·S oil analysis every 500 hours. Other oils: 2,000 hours.

What Hydraulic Oil Does a Cat Use?

Caterpillar's fluids guide, Machine Fluids Recommendations (SEBU6250), names four HYDO Advanced oils as the preferred fill for most Cat hydraulic systems and hydrostatic transmissions. They differ mainly in viscosity, so the choice comes down to the temperatures you work in.

On D-series skid steers, a message by the hydraulic tank states that the system is filled with Cat HYDO Advanced oil. Cat's 2025 data sheet calls HYDO Advanced backward compatible and lists a zinc content of 0.09%, a number that matters when you compare substitutes. HYDO Advanced 10 comes in 1-gallon (309-6932) and 5-gallon (309-6931) containers, among other sizes.

What Is Equivalent to Cat Hydraulic Fluid?

Cat does not publish a brand cross-reference. What it publishes is a ranked fallback list, and every oil on it still has to fit the temperature chart in your manual.

1. Second choice, Cat's own oils: Cat MTO, Cat DEO, Cat DEO-ULS, Cat TDTO, Cat TDTO Cold Weather, Cat TDTO-TMS and Cat DEO-ULS Cold Weather.
2. Third choice, commercial oils: engine oils that meet Cat ECF-1-a, ECF-2 or ECF-3, or oils that meet Cat TO-4 or TO-4M, with at least 0.09% zinc (900 ppm).
3. Minimum viscosity: 6.6 cSt at 212°F (100°C) for any commercial alternative.
4. Biodegradable oils: commercial products must meet Cat BF-2. The older BF-1 standard is obsolete.

The fallback oils cost service life. SEBU6250 puts the drain interval of the second-choice oils at typically 2,000 hours and no more than 4,000, with S·O·S oil analysis required, against 3,000 hours standard for HYDO Advanced. Cat also states that it does not warrant the quality or performance of non-Cat fluids.

Can I Use AW-32 or AW-46 Hydraulic Oil in a Cat?

Not according to Caterpillar. SEBU6250 states that industrial hydraulic oils are not recommended for service fill in Caterpillar hydraulic systems, and Cat's HYDO Advanced data sheet describes industrial oils as the ones often described as anti-wear (AW).

• Water: industrial oils are made to separate water. Cat warns that separated water drawn through a mobile hydraulic system can damage pumps, and worse if it freezes. HYDO Advanced holds small amounts of water in dispersion instead.
• Zinc: Cat recommends at least 900 ppm zinc to protect pumps, motors and valves, and says typical AW industrial oils carry less.
• Viscosity is not the test: Cat's data sheet lists HYDO Advanced 10 at 42 cSt at 104°F (40°C), but Cat rates it as an SAE 10W oil and publishes no ISO grade equivalent.

If a product data sheet says the oil "separates", "sheds" or "releases" water, Cat's advice is to avoid it in your machine.

How Do I Check a Store-Brand Oil Against Cat's Specs?

Cat names no store-brand equivalent, so a product passes only on what its own data sheet shows. Check four things before it goes in the tank:

1. The spec claim: Cat ECF-1-a, ECF-2, ECF-3, TO-4 or TO-4M on the label or data sheet.
2. Zinc: at least 0.09% (900 ppm).
3. Viscosity: at least 6.6 cSt at 100°C, in a grade suited to your temperature range on your manual's chart.
4. Water handling: not an oil designed to separate or shed water.

Even an oil that passes is a third-choice fill with a shorter drain interval. Cat also advises, for best results, not to mix oil types or oil brands in one compartment.

Which HYDO Advanced Grade Fits Your Climate?

Cat's manuals choose the grade by the coldest air temperature around the machine when you start and work it, then check the maximum against the hottest day you expect. Where more than one oil fits, the manual says to use the highest viscosity allowed for the temperature.

• Most work: HYDO Advanced 10 covers -4°F to 104°F. The 216B3 to 259B3 manual extends it to 122°F on machines with the High Ambient Cooling Attachment.
• Consistently hot work: HYDO Advanced 20 (23°F to 113°F) or HYDO Advanced 30. Cat's data sheets start HYDO Advanced 30 at 50°F, while SEBU6250 and the loader manuals list 32°F.
• Below -4°F: the D-series manual says the 10W factory fill must be replaced with a cold-weather oil from the chart and points to Cat's Cold-Weather Recommendations (SEBU5898). Cat TDTO Cold Weather SAE 0W-20 and Cat DEO-ULS Cold Weather SAE 0W-40 are both rated down to -40°F.
• Hydraulic hammers: Cat says not to use SAE 0W or 5W oils on machines that run one.

Warm-up matters as well. The D-series manual has you run the engine for 5 minutes, then cycle the tilt control for 3 minutes, or 8 minutes below 32°F, before you put the machine to work.

What Hydraulic Fluid Does a Cat Skid Steer Take?

The same HYDO Advanced oils as the rest of the range. SEBU6250 covers skid steers from the 216 through the 299 and sends their hydraulic systems to the main hydraulic chart, so HYDO Advanced 10 is the standard fill on Cat skid steer, compact track and multi terrain loaders.

The D-series figures come from Cat's operation and maintenance manual and are refill amounts for the tank. The whole system holds more: the 262D spec sheet lists 13.7 gallons for the hydraulic system against 10.3 for the tank.

Do the Hydrostatic Drive and Loader Hydraulics Share Oil?

Yes. Cat's documents treat them as one oil system: the fluids guide gives a single chart for "Hydraulic System and Hydrostatic Transmissions", the D-series refill table lists one hydraulic tank with no separate hydrostatic compartment, and the oil change drains that one tank and replaces one hydraulic filter.

• Hydrostatic drive: the drive pumps and motors that move the machine are covered by the same oil chart and the same oil change.
• Loader hydraulics: the lift, tilt and auxiliary circuits.
• Not shared: the drive chain cases on wheeled skid steers and the final drives on track and multi terrain loaders, which have their own oils and fill points.

One practical result: topping up the tank with a different oil changes what both the drive and the loader are running on.

What Goes in a Cat Skid Steer Chain Case?

Engine oil. Both the D-series manual and the 216B3 to 259B3 manual list Cat diesel engine oils for the skid steer drive chain case, not hydraulic oil.

• Cat DEO-ULS Cold Weather SAE 0W-40: -40°F to 104°F
• Cat DEO-ULS or Cat DEO SAE 10W-30: 0°F to 104°F
• Cat DEO SAE 15W-40: 15°F to 122°F

Each side is filled to the bottom of the threads on the fill port, and D-series capacities run from 1.8 gallons per side on the 226D and 232D to 3.3 gallons on the 246D and 262D. Compact track and multi terrain loaders have final drives instead, filled with Cat Synthetic GO SAE 75W-140. This is a real difference from Bobcat, whose chaincase takes the same fluid as its hydraulics, as our Bobcat hydraulic fluid guide explains.

How Often Should Cat Hydraulic Oil and Filters Be Changed?

It depends on the loader generation and the oil in the tank. These intervals come from Cat's two compact-loader manuals that we checked; other Cat machines have their own schedules in their manuals.

One catch on the long interval: the D-series manual says that if HYDO Advanced 10 is contaminated by 10% or more with other oils, you fall back to the non-HYDO Advanced schedule. The same manual has you replace the hydraulic tank breather every 500 hours.

Which Hydraulic Filters Should I Replace With the Oil?

Cat's oil-change procedure includes a new hydraulic filter every time, and the filter style depends on the generation. The 216B3 to 259B3 loaders and C-series machines such as the 262C use a spin-on filter, tightened by the index marks printed on it. D-series machines use an element inside a canister, and the 2024 Cat 260 lists cartridge-type supply and return filters.

For machines with spin-on filters, these aftermarket replacements meet or exceed OEM specifications. Fitment is shown as each listing states it:

• Skid steer, track and multi terrain loaders: Hydraulic filter, replacement for CAT 3I0549. The listing shows fitment for Cat skid steers from the 216 through the 272C, compact track loaders from the 247 through the 297C, and the 267B, 277B, 277C and 287B multi terrain loaders.
• Backhoe loaders and telehandlers: Spin-on hydraulic filter, replacement for CAT 1081153. The listing shows fitment for the 416B through 446B backhoes and the TH62, TH63, TH82, TH83 and TH103 telehandlers.
• Crawler dozers: Spin-on hydraulic filter, replacement for CAT 1446691. The listing shows fitment for D3G, D4G, D5G, D3K, D4K, D5K, D5N and D6N dozers, among other machines.
• Older dozers: Spin-on hydraulic filter, replacement for CAT 85261. The listing shows fitment for D5H, D6M and D8L dozers, among others.

Filter part numbers vary by serial number, and it is the customer's responsibility to verify fitment before ordering. Send your model, serial number and the OEM number to sales@partsonline.com and we will check it for you. Browse the full range in hydraulic filters and our Caterpillar parts collection.

How Do I Check the Hydraulic Oil Level on a Cat Skid Steer?

Check it daily, before the shift. The D-series manual's procedure:

1. Park on level ground and lower the work tool to the ground.
2. Turn off the engine and wait about 5 minutes.
3. Read the gauge: the green area on a needle gauge, or midway between the lines on a sight gauge.
4. Top off through the hydraulic oil filler. If you run hydraulic attachments often, you can fill closer to the upper limit, but do not overfill the tank.

After an oil change, check the level with the loader arms fully lowered. Bubbles in the oil mean air is getting into the system, and Cat's manual says to inspect the suction hoses and hose clamps. Always relieve hydraulic pressure before opening any line, and consult a certified mechanic for hydraulic repairs.

Frequently Asked Questions

What hydraulic oil does a Cat use?

Most Cat machines use Cat HYDO Advanced 10, an SAE 10W oil that is the typical factory fill. HYDO Advanced 20 and 30 suit hotter climates, and Bio HYDO Advanced is the factory fill where biodegradable oil is required.

What is equivalent to Cat hydraulic fluid?

Cat publishes no brand equivalent. Its fluids guide lists Cat MTO, DEO and TDTO oils as second choice, then commercial oils that meet Cat ECF-1-a, ECF-2, ECF-3, TO-4 or TO-4M with at least 900 ppm zinc.

What is compatible with Cat hydraulic oil?

Cat's second-choice oils are approved for the same systems, but Cat advises not mixing oil types or brands for best results. When switching to HYDO Advanced, keep the previous oil below 10% of the fill to keep the longer drain interval.

What is the NAPA equivalent of Caterpillar hydraulic oil?

Caterpillar does not name a NAPA equivalent, or any other brand. Check a product's data sheet for a Cat TO-4 or ECF claim, at least 900 ppm zinc and at least 6.6 cSt at 100°C, and skip industrial AW oils.

What is Cat HYDO Advanced 10?

It is Cat's SAE 10W hydraulic oil for -4°F to 104°F, rated for 3,000-hour drains, or 6,000 hours with S·O·S oil analysis every 500 hours. It comes in 1-gallon (309-6932) and 5-gallon (309-6931) containers, among other sizes.

What does the symbol on a Cat hydraulic tank mean?

Cat puts a symbol on the hydraulic tank of machines filled with biodegradable hydraulic oil. A film near the filler cap marks machines filled with arctic or synthetic oil, so match the fill before you top up.

Is there a Cat hydraulic oil additive?

Yes. Caterpillar's fluids guide says its 1U-9891 additive, a friction modifier, may be used if noise is a problem in the hydraulic system.