How to Change Hydraulic Oil in Your Log Splitter or Pump Engine

Why Hydraulic Oil Matters

Hydraulic oil keeps your log splitter or pump engine running smoothly. Over time, the oil breaks down, gets dirty, and loses its ability to protect moving parts. Changing it regularly is one of the best ways to keep your equipment working well and lasting longer.

What You'll Need

Before you start, gather these items:

• New hydraulic oil (check your equipment's manual for the right type and amount)
• An oil drain pan or bucket
• Wrenches or sockets that fit your drain plug
• A funnel
• Clean rags or paper towels
• Safety glasses
• Work gloves
• A jack or blocks (if you need to lift the equipment safely)

Step 1: Prepare Your Equipment

Park your log splitter or pump on level ground. Let the engine cool completely—hot hydraulic oil can burn your skin. Turn off the engine and remove the key so it won't start by mistake.

If your equipment has a dipstick or sight glass, note the current oil level. This helps you know how much new oil to add later.

Step 2: Find the Drain Plug

Look at the bottom of the hydraulic tank or reservoir. The drain plug is usually a bolt or valve at the lowest point. Check your equipment's manual if you're not sure where it is. Some equipment may have more than one drain plug.

Step 3: Drain the Old Oil

Place your drain pan underneath the plug. Slowly turn the plug counterclockwise by hand first, then use a wrench to finish unscrewing it. Let the old oil drain completely—this may take 10 to 20 minutes. Tilt or rock the equipment gently if needed to drain more thoroughly.

Once the oil stops dripping, wipe the plug clean with a rag.

Step 4: Replace or Clean the Filter (If Your Equipment Has One)

Some log splitters and pumps have a hydraulic filter. If yours does, now is a good time to change or clean it. Follow your manual's instructions. A new or clean filter helps keep fresh oil clean longer.

Step 5: Reinstall the Drain Plug

Screw the drain plug back in by hand first. Then use a wrench to tighten it firmly—but don't over-tighten, as this can strip the threads. Wipe away any spilled oil.

Step 6: Add New Hydraulic Oil

Place a funnel into the fill opening on top of the hydraulic tank. Slowly pour in the new oil. Pour only the amount recommended in your manual. Overfilling can cause problems just like underfilling.

Step 7: Check the Level

Once you've added oil, check the level using the dipstick or sight glass. The oil should reach the "full" mark. Add a little more if needed, or drain some if you added too much.

Step 8: Run the Engine

Start the engine and let it run for a few minutes at low speed. This helps the new oil circulate through the system. Turn off the engine and let it cool for a few minutes.

Check the oil level again. The level may have changed slightly as the oil settled. Add more if the level is now low.

When to Change Your Oil

Check your equipment's manual for how often to change hydraulic oil. Most log splitters and pump engines need an oil change every 50 to 100 hours of use, or at least once a year. If you use your equipment heavily or in dusty conditions, you may need to change it more often.

Tips for Success

• Always use the type of hydraulic oil your manual specifies. Using the wrong type can damage your equipment.
• Keep the work area clean to avoid getting dirt in the hydraulic system.
• Dispose of old hydraulic oil properly. Many auto parts stores and service centers will take used oil for recycling.
• Write down the date and hours when you changed the oil so you remember when the next change is due.
• If you notice leaks or the oil looks very dark or smells burnt, contact a service technician.