How to Change the Oil in a 2010 GAS GAS TXT PRO 125

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Regularly changing the oil on your 2010 GAS GAS TXT PRO 125 is crucial to keeping your trial bike performing at its best. This guide from MotoSport.com will walk you step-by-step through the oil change process specific to this model, covering the recommended oil, torque guidance, and common pitfalls to avoid. Follow these instructions and your TXT PRO 125 will continue to deliver reliable rides on the trail and in competition.

Tools & Supplies Needed

  • Correct size spanner or socket for the drain plug (commonly 13mm, but check your exact model)
  • Drain pan
  • Funnel
  • Clean rags or shop towels
  • Replacement crush washer or sealing washer (recommended)
  • Transmission oil (Recommended: 370cc of NILS CLUTCH TRIAL gear oil or a suitable equivalent for two-stroke transmissions)
  • Gloves (optional, but helps keep hands clean)

Step-by-Step Process

  1. Prep Your Bike
    • Start the engine and let it run for a few minutes. This warms up the oil, helping it drain more thoroughly.
    • Kill the engine and place the bike on a stable stand so it’s upright and secure.
  2. Remove the Drain Bolt
    • Locate the oil drain bolt on the bottom of the engine case. Place your drain pan directly beneath it.
    • Using the correct size spanner or socket, carefully loosen and remove the drain bolt.
    • Let the oil flow into the pan. Inspect the old oil for contamination or metal shavings–potential signs of internal wear.
  3. Replace the Washer
    • It's a good practice to replace the crush washer or sealing washer on the drain bolt each time. This helps prevent leaks.
  4. Reinstall the Drain Bolt
    • Once the oil has completely finished draining, clean the area around the drain plug hole with a rag.
    • Install the drain bolt (with new washer), and torque it to snug–do not overtighten. Stripped threads are a common DIY pitfall—just snug is enough to seal, not forcefully tight.
  5. Fill with Fresh Oil
    • Remove the oil fill cap on the top of the right engine case.
    • Using a funnel, add 370cc of recommended gear oil (NILS CLUTCH TRIAL or a suitable equivalent). For most riding conditions, a premium synthetic gear oil is best for smooth clutch action and gearbox longevity.
    • Reinstall and hand-tighten the oil fill cap.
  6. Final Checks
    • Start the engine and let it run for about one minute, then shut it off. Check for oil leaks, especially near the drain plug.
    • Verify oil level following the manufacturer’s method (sight glass or dipstick, if equipped).
    • Dispose of used oil responsibly–take it to a recycling center, never dump down drains or on the ground.

Model-Specific Tips & Callouts for 2010 GAS GAS TXT PRO 125

  • Transmission Oil Capacity: 370cc is the factory specification for this model year and engine size. Always measure to avoid overfilling as this can cause clutch drag or shifting issues.
  • Oil Selection: GAS GAS recommends a specialist gear oil such as NILS CLUTCH TRIAL. Many experienced riders also use premium synthetic two-stroke gear oils designed for wet clutches. Avoid using standard motor oil, as it may negatively impact the clutch’s performance or accelerate wear

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  • Drain Plug Torque: The crankcase is light alloy; overtightening the drain plug commonly causes stripped threads. Tighten until just snug–never force it–using hand tools and a fresh washer each time

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  • Clutch Feel: If you notice clutch drag or a notchy feel after the oil change, confirm you used the correct oil type and quantity. This model has a sensitive hydraulic clutch, and the wrong oil can affect operation.
  • Routine Checks: Each oil change is a good opportunity to inspect the air filter and clean if necessary, as contaminant ingress can also show up in your transmission oil.

Frequently Asked Questions

  • How often should I change my oil? GAS GAS typically recommends changing the transmission oil every 10–20 hours of ride time, or after any wet/muddy event.
  • Is it normal for the drained oil to look milky? No. Milky oil can indicate water ingress–check your seals and gaskets.
  • I lost the drain plug washer. Can I reuse the old one? In an emergency, yes, but it’s best to always fit a new washer to ensure a proper seal and avoid leaks.

By following this guide for the 2010 GAS GAS TXT PRO 125, you ensure your motorcycle’s clutch and gearbox components are protected and functioning optimally. For all your oils, filters, and tools, MotoSport.com carries premium gear to make garage work fast and easy.

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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.