How to Change the Oil in a 2009 GAS GAS TXT PRO 300: A MotoSport.com Exclusive Guide

Shop parts for a 2009 GAS GAS TXT PRO 300 Dirt Bike.

Changing the transmission oil in your 2009 GAS GAS TXT PRO 300 is a critical maintenance task to ensure optimal clutch function, keep internal gears properly lubricated, and extend the bike's overall life. This guide is proprietary to MotoSport.com and walks you through the entire process, with step-by-step instructions, tools required, and model-specific insights for your TXT PRO 300.

Tools and Supplies Needed

  • 17mm drain bolt socket and ratchet (verify exact size as owner’s manual may differ; 17mm is common for drain plugs)
  • Torque wrench (with Newton-meter scale for precise tightening)
  • Drain pan
  • Funnel or oil fill tube
  • Clean shop rags
  • Gloves (optional, but recommended)
  • Replacement crush washer or O-ring for drain plug (optional, but advised for every oil change)
  • Gear oil for trials motorcycles: Use a high quality synthetic or semi-synthetic 2-stroke gear oil, rated at SAE 75W or recommended for wet clutches. The OEM recommendation for late-model TXT 300 is NILS Clutch Trial oil, capacity 370cc (check your owner’s manual for latest recommendations) .
  • Measuring cup for precise oil quantity

Preparation Steps

  • Start the motorcycle and let it idle for 2–3 minutes, then shut it off. This ensures the oil flows better during draining and helps flush contaminants .
  • Place your bike upright on a stand or kickstand with enough workspace on both sides.
  • Inspect the engine and drain area for dirt and debris. Clean the area around the drain plug with a rag to prevent grime from entering the gearbox.

Step-by-Step Transmission Oil Change Procedure

  1. Locate the Drain Bolt
    • On the 2009 GAS GAS TXT PRO 300, the transmission oil drain bolt is usually on the lower right side of the engine case, underneath the bike. Identify it before proceeding.
  2. Drain the Old Oil
    • Position your drain pan directly under the drain bolt.
    • Use your socket and ratchet to carefully loosen and remove the drain bolt. Let the old oil completely drain into the pan.
    • Inspect the oil for metal flakes or unusual contamination, which may indicate internal wear.
    • Remove and inspect the drain plug washer or O-ring. Replace if visibly damaged or worn.
  3. Reinstall the Drain Bolt
    • Reattach the crush washer or O-ring to the drain bolt.
    • Hand-thread the bolt back in, then use a torque wrench to tighten to the manufacturer’s specification. For similar models, this is typically 23.5 to 25.5 Nm . Avoid overtightening to prevent stripping the threads .
    • Wipe away any oil spills around the bolt area with a clean rag.
  4. Add New Oil
    • Remove the oil filler cap located on the top of the right engine case.
    • Using your measuring cup, pour in 370cc (0.37L) of the specified gear oil .
    • Use a funnel to avoid leaks, and pour slowly to prevent overfilling. Allow the oil to settle.
  5. Replace the Filler Cap & Check for Leaks
    • Screw the oil fill cap back in by hand, ensuring it’s snug but not overtightened.
    • Start the motorcycle and let it idle for 1–2 minutes, then shut it off.
    • Visually inspect under the motorcycle for any signs of leakage from the drain bolt or filler cap area.
  6. Proper Disposal
    • Pour the old oil from your drain pan into a sealed container and take it to your nearest recycling facility or a MotoSport.com location that offers oil recycling services.

Model-Specific Call-outs for the 2009 GAS GAS TXT PRO 300

  • Oil Capacity: 370cc of transmission oil is a critical spec for the TXT PRO 300 (2009) .
  • Oil Type: Use a quality synthetic or semi-synthetic 2-stroke transmission oil, or specialized “Clutch Trial” oils designed for wet clutch applications. Do not substitute with standard engine oil or cheap automotive gear oil, as the wet clutch demands proper chemistry for performance and durability .
  • Drain Plug Location: Confirm the correct drain plug – TXT PRO engines have a dedicated gearbox drain. Do not remove the engine coolant or primary drive drain by mistake.
  • Torque Caution: The magnesium or lightweight alloy cases in trials bikes are prone to stripping if overtightened. Always use a torque wrench on the drain bolt and filler plug .
  • Oil Check Window: This model does not always have an oil sight glass; rely on measured refill quantity for accuracy.

Extra Tips from MotoSport.com Techs

  • If riding in extreme conditions or participating in frequent competitions, change the oil more often than the manual advises.
  • Keep an eye on clutch feel: If the clutch begins to drag or feel inconsistent, consider changing oil sooner and ensure you are using the correct specification.
  • Record your maintenance: Keeping a log of oil changes can alert you to developing mechanical issues before they become serious.

Performing regular oil changes on your 2009 GAS GAS TXT PRO 300 keeps the gearbox and clutch in optimal shape for the precision riding and reliability you expect. For all your GasGas parts, fluids, and accessories, trust MotoSport.com to keep you—and your trials bike—dialed in.

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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.