Gehl Skid Steer Hydraulic Oil Change

This guide provides a comprehensive, step-by-step walkthrough for replacing the hydraulic oil and filter on your Gehl skid steer. It includes parts options from Tractor Supply Company (TSC) and curated video tutorials.

1. Parts & Materials (Tractor Supply Options)

Gehl skid steers typically require an ISO VG46 (AW46) Anti-Wear Hydraulic Fluid. Always double-check your specific model's operator manual, as some older models might require a Universal Tractor Fluid (UTF).

• Top Choice: Traveller Premium Anti-Wear Hydraulic Fluid (AW46)
  Pros: Highly affordable ($35–$50 per 5-gal bucket), meets standard specs, provides excellent anti-wear and anti-foaming protection.
• Alternative for Older/Weeping Seals: Mystik JT-9 LeakShield AW Hydraulic Oil 46
  Pros: Contains synthetic seal swell agents to prevent minor leaks. Dyed green to easily spot leaks.

Filters & Tools Needed:

• Hydraulic Filter (OEM Gehl or high-quality aftermarket like Wix/Baldwin)
• Large Catch Pan (systems hold 10–20+ gallons)
• Sockets/Wrenches for drain plug
• Filter Wrench and Rags

2. Step-by-Step Procedure

Step 1: Preparation & Positioning

1. Park the skid steer on a flat, level surface.
2. Fully lower the lift arms to the ground.
3. Turn off the engine, remove the key, and allow the system to cool down.

Step 2: Locate the Drain Plug

• Standard Location: On most mid-to-large frame Gehl skid steers (e.g., SL4640, SL4840, SL4510), the hydraulic reservoir drain plug is located on the inside bottom of the right riser.

Step 3: Drain the System

1. Clean the area around the drain plug to prevent dirt from entering the system.
2. Place your large capacity catch pan directly beneath the plug.
3. Slowly loosen and remove the drain plug, allowing the fluid to drain completely.

Step 4: Inspect the Magnetic Drain Plug

Many Gehl drain plugs are magnetic to catch metal debris. Inspecting this plug is critical:

• Normal: A small amount of fine, "graphite-like" paste or metallic "fuzz".
• Warning Sign: Distinct visible flakes, curled shavings, or larger chunks of metal (steel/iron). This indicates abnormal wear (e.g., failing bearings or pump internals).

Step 5: Replace the Hydraulic Filter

1. Locate the hydraulic filter canister (often near the rear engine compartment) and clean the housing area.
2. Use a filter wrench to spin off the old filter. Have a rag ready to catch drips.
3. Take the new filter and apply a thin layer of clean hydraulic oil to the rubber O-ring seal.
4. Thread on the new filter by hand until the seal makes contact, then tighten it 1/2 to 3/4 turn past contact.

Step 6: Refill and Bleed the System

1. Clean the magnetic drain plug, reinstall it, and tighten it securely.
2. Locate the hydraulic fill port and slowly pour in the new AW46 hydraulic fluid.
3. Monitor the sight glass (typically located at the right rear of the machine) to ensure you do not overfill. Fill to the recommended line.
4. Bleed the System: Start the engine and let it run at low idle. Cycle the lift arms up and down, and tilt the bucket cylinders back and forth several times to push out trapped air.
5. Lower the arms, shut off the engine, and re-check the sight glass. Add more fluid if the level has dropped.

3. Video Tutorials & Visual Guides