How to Perform a Bull Series UTV Differential Gear Oil Change

Owning a UTV expands your ability to work the land, making it easier to access remote areas while accommodating more passengers and heavier payloads. To ensure your workhorse is in fighting shape, be sure to perform scheduled maintenance tasks, like the differential gear oil change. Here’s when and how to perform this task. 

For information on how to complete a UTV engine oil change, read this article.

When to Perform a Differential Gear Oil Change

How often should you change the differential gear oil? The differential gear oil in your UTV should be changed during your initial 20 hours maintenance check and every 300 hours or twelve months after that, whichever comes first. 

Equipment Needed to Complete a Differential Gear Oil Change

Before you begin, ensure that you have everything you need to perform this type of oil change. 

  • SAE 80 API GL-4 Hypoid Gear Oil. You’ll need a very small amount of this specific oil type. 
  • Oil Drain Pan (and Shop Towels). You will be draining the old oil from your UTV, so have a waste oil pan ready, and shop towels in case it gets messy. 
  • New Filler Bolt Gasket and New Drain Bolt Gasket. This is the perfect time to inspect your filler bolt gasket and drain bolt gasket. Have new ones on hand in case the old ones need to be replaced. 
  • Torque Wrench. To ensure bolts are secured with the right amount of foot pounds, you’ll want a torque wrench.  
  • 21 mm Wrench and 21 mm Socket. You will need these tools to access your gear casing.
  • 5 mm Hex Socket and Hex Socket Extension. The extension will make it easier to access the gear casing.
  • Safety Goggles and Gloves. Whenever you’re dealing with oil, it’s good to protect your eyes and skin from irritation. Safety goggles and nitrile or latex gloves work great. 
  • Tire Chocks. Keep your UTV stable during the oil change using tire chocks.

How to Perform a Differential Gear Oil Change

Before you get started, move your UTV onto a flat and level surface. Engage the parking brake and chock the tires before you begin working under the unit. Ensure that your engine is off and has cooled. 

  1. Place Oil Drain Pan. First, place your oil drain pain under the differential gear case to collect the used oil.
  2. Loosen Differential Gear Oil Filler Bolt. Using the 21 mm wrench, loosen, but do not remove the differential gear oil filler bolt.
  3. Remove Drain Bolt. Using the 5 mm hex socket with extension and ratchet, remove the differential gear oil drain bolt and the gasket to drain the oil. 
  4. Remove Filler Bolt and Allow Oil to Drain. As the oil starts to drain, now is the time to remove the filler bolt that you loosened in step 2. This will allow a thorough drain of the gear casing. 
  5. Install New Oil Drain Bolt and Gasket. Once the oil is completely drained, install the new differential gear oil drain bolt and its new gasket.  Be sure to clean the area thoroughly with your shop towel before reinstalling the filler bolt. Tighten the bolt to 7.2 foot pounds of torque. 
  6. Refill the Differential Gear Case. Refill the differential gear case with SAE 80 API GL-4 hypoid gear oil. Pour slowly, as only 0.18 liters of oil is required.
  7. Inspect and Replace Oil Filler Bolt if Necessary. Inspect the oil filler bolt for damage, and replace if necessary. The Yanmar part number for this bolt is 1NF000-01500. 
  8. Reinstall Differential Gear Oil Filler Bolt. Finally, reinstall the new (or newly inspected) differential gear oil filler bolt and gasket. Torque the bolt to 17 foot pounds. 
  9. Clean Up. When the job is done, be sure to clean any spilled oil and check for leakage. If oil leakage is found, check for the cause. For more tips, consult your owner’s manual. 

Your oil change is complete! This is a quick, easy task, but necessary to keep your UTV on the trails for years to come. 

Connect With Yanmar

At Yanmar, we pride ourselves on our industry-leading support. From UTVs to compact tractors, we’re here to answer questions and give you the resources you need to succeed. Please don’t hesitate to connect with us online or give us a call at 678-551-7369.

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