How to Change Hydraulic Oil on Skid Steers and Excavators

Why Hydraulic Oil Matters for Your Equipment

Hydraulic oil is the lifeblood of skid steers and excavators. It powers the cylinders, motors, and valves that make these machines work. Over time, hydraulic oil breaks down from heat, dirt, and use. Changing it regularly keeps your equipment running smoothly and helps prevent costly damage to your hydraulic system.

When hydraulic oil degrades, it loses its ability to protect moving parts and transfer power efficiently. This can lead to slower operation, increased wear on components, and eventually expensive repairs. Regular oil changes are one of the most cost-effective ways to maintain your equipment and keep it performing at its best.

What You'll Need Before You Start

Gather these items before you begin the oil change process:

• New hydraulic oil (check your equipment manual for the correct type and amount)
• An oil drain pan or container large enough to hold all the old oil
• Wrenches or sockets that fit your equipment's drain plugs
• A new hydraulic filter (if your machine has one)
• A filter wrench or strap wrench for removing the old filter
• Clean rags or paper towels
• Safety glasses and gloves to protect yourself
• A level, flat work surface away from traffic
• A clean funnel for pouring new oil

Having all your supplies ready before you start saves time and prevents you from leaving the machine partially disassembled. Store your new oil in a clean, dry place until you're ready to use it. Check the oil container to make sure it's the exact type your manual recommends—using the wrong oil can damage your hydraulic system.

Step 1: Prepare Your Machine

Park your skid steer or excavator on level ground in a safe location. Turn off the engine and let it cool for at least 15 minutes. Warm oil drains faster, but hot oil can cause serious burns. Engage the parking brake and lower all hydraulic arms and attachments to the ground. This relieves pressure in the system and makes draining safer for you.

Take a moment to inspect the area around your machine. Make sure there are no obstacles that could interfere with your work. If you're working outdoors, consider the weather—avoid changing oil on extremely hot days when the oil will be too thin, or on cold days when it will drain very slowly. A moderate temperature makes the job easier and safer.

Step 2: Locate the Drain Plug

Check your equipment manual to find where the hydraulic reservoir drain plug is located. On most skid steers and excavators, it's at the bottom or side of the main hydraulic tank. The manual will show you exactly where to look and may include a diagram of your specific model.

Before you open anything, place your drain pan underneath the drain plug location. Position it so it will catch all the oil as it flows out. This prevents spills that could contaminate the ground and makes cleanup much easier. If your drain pan is small, have a second container ready in case you need it.

Step 3: Drain the Old Oil

Use your wrench to slowly loosen the drain plug. Turn it counterclockwise until you can feel it's loose enough to remove by hand. Once it's loose, carefully unscrew it the rest of the way by hand—it may still be warm even after cooling. Let the old oil flow completely into your drain pan. This may take several minutes depending on how much oil your machine holds and how thick it is.

While the oil drains, wipe the drain plug clean with a rag and inspect it for damage. Look for cracks, stripped threads, or excessive wear. If the plug looks damaged, you may need to replace it with a new one. Once all the oil has finished draining and the flow has stopped completely, set the cleaned drain plug aside in a safe place where you won't lose it.

Step 4: Replace the Hydraulic Filter (If Equipped)

If your machine has a hydraulic filter, now is the time to change it. The filter is usually located near the reservoir or along the hydraulic lines. Use a filter wrench or strap wrench to turn the old filter counterclockwise until it comes free from its housing. Be careful—there may still be some oil inside the filter that will drip out.

Once you've removed the old filter, wipe the filter housing clean with a rag to remove any dirt or debris. This ensures a good seal with the new filter. Take your new filter and apply a thin layer of new hydraulic oil to the rubber gasket on the threaded end. This helps create a watertight seal. Screw the new filter on by hand until the gasket just touches the housing, then turn it an additional three-quarter turn. Don't over-tighten it—hand-tight plus three-quarter turn is the correct amount.

Step 5: Reinstall the Drain Plug

Clean the drain plug threads thoroughly with a clean rag to remove any dirt or old oil. Inspect the threads on both the plug and the reservoir to make sure they're not damaged. Screw the drain plug back in by hand first to make sure it threads smoothly and easily.

Once the plug is hand-tight, use your wrench to tighten it further. Apply firm, steady pressure, but don't over-tighten—you could strip the threads and create a leak that's difficult to fix. The plug should be snug enough that it won't leak, but not so tight that you'll have trouble removing it next time you change the oil.

Step 6: Add New Hydraulic Oil

Open the filler cap on top of the hydraulic reservoir. Set it aside in a clean place. Using a clean funnel, pour in the new hydraulic oil slowly and carefully. Pouring slowly prevents splashing and helps you avoid overfilling. Check your equipment manual for the exact amount of oil your machine needs—this varies significantly between different models and sizes.

Most machines have a sight glass or dipstick on the side of the reservoir so you can see the oil level as you fill. Fill to the recommended mark on the sight glass or to the "full" line on the dipstick. Don't overfill—too much oil can damage seals and cause leaks. Once you've reached the correct level, replace the filler cap securely.

Step 7: Start the Engine and Check for Leaks

Start the engine and let it run at idle for a few minutes. This circulates the new oil through the system and helps it reach all the components. While the engine is running, carefully watch for leaks around the drain plug, the filter, and any other connections you worked on. Look for oil dripping or spraying from these areas.

After a few minutes of running, stop the engine and let it cool for about 10 minutes. Then check the oil level again using the sight glass or dipstick. The level may have dropped slightly as the new oil fills the filter and lines. Top off the oil if needed to bring it back to the recommended level. This ensures your system has enough oil to operate properly.

Step 8: Dispose of Old Oil Properly

Never pour old hydraulic oil down a drain, into the ground, or into a storm sewer. Hydraulic oil is toxic and can contaminate groundwater and harm the environment. Instead, take your used oil to a recycling center, service station, or hazardous waste facility in your area. Many places will take used oil for free or charge only a small fee.

Store your old oil in a clean, sealed container until you can take it for disposal. Label the container clearly so there's no confusion about what it contains. Some communities offer free oil disposal days where residents can drop off used oil at no cost. Check with your local waste management department to learn about disposal options in your area.

How Often Should You Change Hydraulic Oil?

Check your equipment manual for the recommended oil change interval. Most skid steers and excavators need a hydraulic oil change every 500 to 2,000 hours of use, depending on the machine model and operating conditions. Some machines may need more frequent changes if they operate in dusty, sandy, or extremely hot environments.

Keeping a maintenance log helps you track when you last changed the oil and when the next change is due. Write down the date, the hours on the machine, and any observations about the oil condition. This record is valuable if you ever sell the equipment, and it helps you stay on a consistent maintenance schedule. Sticking to the recommended interval prevents problems and keeps your equipment reliable.

Signs Your Hydraulic Oil Needs Attention

Watch for these warning signs that your hydraulic oil may need changing sooner than scheduled:

• The oil appears dark brown or black instead of its normal amber color
• The oil has a burnt smell, like charred metal or rubber
• You notice sluggish or slow movement in hydraulic arms or attachments
• The machine makes unusual noises like grinding, squealing, or knocking
• You see leaks or puddles of oil under the equipment
• The hydraulic system seems to overheat during normal operation

If you spot any of these issues, have your hydraulic system inspected by a may have access to technician before continuing to use the machine. Ignoring warning signs can lead to complete system failure and expensive repairs. Taking action early when you notice problems can save you time and money in the long run.

Key Takeaways

Changing hydraulic oil is a straightforward maintenance task that keeps your skid steer or excavator in good working order. By following these steps carefully and sticking to your maintenance schedule, you'll extend the life of your equipment and avoid costly downtime. Regular oil changes protect your investment and keep your machine running reliably.

Always refer to your specific machine's manual for exact procedures, oil specifications, and recommended change intervals. Different models may have slight variations in where components are located or how much oil they hold. Taking time to do the job right the first time ensures your equipment stays in top condition for years to come.

Frequently Asked Questions

Can I mix different brands of hydraulic oil?

It's best to use the same brand and type of hydraulic oil that your manual recommends. Mixing different brands or types can sometimes cause chemical reactions that reduce the oil's effectiveness. If you must add oil between changes, use the same product you put in originally. When you perform a full oil change, you can switch to a different brand if it meets your equipment's specifications, since you're replacing all the old oil.

What should I do if I spill hydraulic oil?

If you spill hydraulic oil during the change, clean it up immediately to prevent environmental contamination. Use absorbent materials like cat litter, sand, or oil absorbent pads to soak up the spill. Once absorbed, place the material in a sealed container and dispose of it as hazardous waste at a facility that accepts it. Never wash spilled oil into storm drains or allow it to soak into the ground.

How can I tell if my hydraulic filter is clogged?

A clogged hydraulic filter can reduce system performance and damage your equipment. Signs of a clogged filter include sluggish machine operation, unusual noises from the hydraulic system, or a warning light on your equipment's dashboard if it has one. If you suspect a clogged filter, change it immediately. As a general rule, change the filter every time you change the hydraulic oil, or more often if you work in dusty conditions.