How to Change the Oil in a 2021 GAS GAS TXT RACING 300

Shop parts for a 2021 GAS GAS TXT RACING 300 Dirt Bike.

This guide, proprietary to MotoSport.com, details everything you need to know to confidently change the transmission oil in your 2021 GAS GAS TXT RACING 300. Performing regular oil changes protects your clutch and gearbox, ensuring peak performance and longevity for your dirt bike. Let's get started.

Tools and Supplies Needed

  • 4mm and 5mm Allen (hex) wrenches (for access panels or skid plate removal, if needed)
  • 13mm or 17mm wrench/socket (verify drain bolt size for your bike)
  • Oil drain pan
  • Rags or shop towels
  • Funnel
  • Measuring cup (graduated, for precise oil amount)
  • Genuine replacement crush washer for the drain bolt (recommended)
  • NILS CLUTCH TRIAL transmission oil (or comparable high-quality 75W gear oil)
  • Torque wrench (recommended, to avoid over-tightening)
  • Gloves and eye protection (for safety)

Specifications and Call-Outs for 2021 GAS GAS TXT RACING 300

  • Transmission Oil Capacity:– 370cc (0.37 L)
  • Oil Type:– NILS CLUTCH TRIAL (or similar SAE 75W gear oil)
  • Change Interval:– Every 30 hours of riding, or more frequently in severe conditions
  • Unique Feature:– Diaphragm clutch system—keep oil topped off and fresh for the best clutch feel and protection

Step-By-Step Oil Change Instructions

  1. Warm Up the Engine
    • Start and run the engine for about 5 minutes. Warming up ensures old oil drains thoroughly and brings contaminates into suspension for removal.
  2. Prepare the Work Area
    • Place the bike on a stable, level surface using a stand.
    • Lay rags under the engine to catch drips.
    • If your model has a skid plate, remove it for easy access to the drain bolt using the appropriate Allen wrench.
  3. Remove the Oil Filler Cap
    • The oil filler cap is usually on the right-hand side of the engine. Remove this now to prevent a vacuum, allowing oil to drain more easily.
  4. Drain the Old Oil
    • Locate the transmission oil drain bolt beneath the engine–usually at the lowest point of the crankcase.
    • Place your oil drain pan beneath this area.
    • Using the correct size wrench, carefully loosen and remove the drain bolt. Beware of hot oil if the bike was fully warmed up.
    • Let all old oil drain completely. Slightly tilt the bike from side to side to help remove every drop.
    • Inspect and replace the crush washer on the drain bolt if it's damaged or deformed.
  5. Reinstall the Drain Bolt
    • Wipe the drain bolt and sealing surface on the case clean.
    • Install a new crush washer.
    • Thread in the bolt by hand, then use your wrench to snug it up. Do not overtighten—stripped drain bolts are common mistakes on trials bikes. If using a torque wrench, tighten to the recommended torque (check your owner's manual, typically around 10-15 Nm).
  6. Add New Transmission Oil
    • Using a funnel, slowly pour in 370cc (0.37 L) of fresh NILS CLUTCH TRIAL transmission oil (or equivalent).
    • Allow the oil to settle for a minute, then check for leaks at the drain bolt.
  7. Reinstall the Filler Cap
    • Clean the oil filler threads and cap. Screw the filler cap back on, being careful not to overtighten.
  8. Dispose of Old Oil Responsibly
    • Do not dump oil in the trash or on the ground. Bring it to a proper recycling or hazardous waste facility.
  9. Inspect and Test
    • Wipe down the bike and check for leaks after starting the engine for a minute.
    • If you removed a skid plate, reinstall it now.
    • Ride the bike gently and double check oil levels and for leaks after your first test ride.

Owner's Tips & Model-Specific Notes

  • Always use a measuring cup to pour the precise amount of oil; overfilling and underfilling can both cause gearbox and clutch issues on these bikes.
  • Use a quality transmission oil designed for wet clutches; the GAS GAS uses a diaphragm clutch for excellent feel but is sensitive to oil condition.
  • If your clutch feel changes or becomes inconsistent after an oil change, check you used the correct type and amount of oil.
  • Be gentle with the drain bolt–these cases are soft and it's easy to damage threads.
  • Routinely check for leaks after each oil change, especially around the crush washer and drain bolt.
  • Check your owner's manual if you are unsure of torque specs or for any updates for your specific year and model.

Conclusion

Changing the oil on your 2021 GAS GAS TXT RACING 300 is straightforward and crucial for performance and reliability. Following this guide ensures your bike's gearbox and clutch remain protected, letting you focus on conquering the next section or trail ride with confidence.

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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.