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

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

Keeping your 2021 GAS GAS TXT GP 300 performing at its best relies on routine maintenance, and changing the transmission oil is one of the most vital jobs for prolonged engine life and smooth shifting. This guide, proprietary to MotoSport.com, walks you through the full process, including the tools required, detailed steps, and important call-outs specific to your model. Let’s get started.

Tools and Supplies Needed

  • Socket wrench set (preferably metric, to fit the drain and fill plugs)
  • Drain pan (large enough for the oil volume)
  • Funnel (a small, long neck funnel is best due to fill port access)
  • Clean rags
  • New transmission oil (Manufacturer recommends NILS Clutch Trial or equivalent high-quality 2T transmission oil, capacity 370cc for 2021 TXT GP 300)
  • Torque wrench (for correct tightening of bolts)
  • Cleaning brush (optional: to clean around drain area)
  • Gloves (optional, for clean hands)

Preparation

  • Place the bike on a stable stand, upright and level.
  • Ensure the engine is cool to avoid burns from hot oil.
  • Clean the area around the drain and filler plugs to prevent contaminants from entering the transmission.

Step-by-Step Oil Change Process

  1. Locate the Drain and Fill Plugs
    • The drain plug is typically found on the lower right side of the crankcase. The fill plug is on the engine case, accessible from the side.
  2. Remove the Fill Plug
    • Loosening the fill plug before draining allows air in, enabling the oil to drain fully and quickly.
  3. Place the Drain Pan
    • Slide your drain pan under the drain plug. Make sure it can catch all the oil (just over 370cc).
  4. Remove the Drain Plug
    • Carefully unscrew the drain plug with the appropriate socket.
    • Allow the oil to drain completely. This can take several minutes; tip the bike gently side-to-side for a more complete drain if necessary.
    • Inspect the plug: most have a magnetic tip designed to catch metal debris. Small metal particles are normal, but large chunks suggest internal wear and warrant further inspection .
  5. Clean & Reinstall the Drain Plug
    • Wipe the plug (especially the magnet) clean of debris.
    • Check the drain plug washer or O-ring; replace if it’s damaged or crushed for a proper seal.
    • Thread in the drain plug by hand to avoid cross-threading. Tighten to the manufacturer’s specified torque.
  6. Add Fresh Transmission Oil
    • Using the funnel, pour in 370cc of the recommended oil. Pour slowly to prevent overflow—fill port access is tight, so a narrow funnel is ideal .
    • Double-check the level if your model features an inspection window or level screw (some variants do; always refer to your owner’s manual).
  7. Reinstall the Fill Plug
    • Install and tighten the fill plug, again following any torque setting in your service manual.
  8. Wipe Away Spills & Clean Up
    • Use a rag to wipe up any dripped oil and properly dispose of your used oil at a certified recycling center.
  9. Start the Bike & Circulate the Oil
    • Before hitting the starter, gently kick the engine through by hand a few times to get oil moving through the gears .
    • Start the engine, let it idle for about a minute, and check for leaks around the drain and fill plugs.
    • Shut it off, let it settle, and recheck oil level if your machine has a sight glass or inspection port.

Model-Specific Call-Outs: 2021 GAS GAS TXT GP 300

  • Transmission Oil Capacity: 370cc is correct for the 2021 TXT GP 300 engine. Overfilling or running low can lead to shifting issues and premature clutch wear .
  • Tight Fill Port Clearance: Access to the fill hole is cramped—use a small funnel for better aim and less mess .
  • Magnetic Drain Plug: Briefly check for metal debris at each oil change. Small filings are expected; significant or large pieces indicate mechanical problems .
  • Owner’s Manual Confirmation: Always consult your latest owner’s manual for unique updates (some manuals for adjacent years reference procedures, but the process and capacities remain nearly identical between 2019 and 2021 models) .
  • Clutch Feel: Old or heavily contaminated oil may affect clutch responsiveness and increase drag; clean oil improves lever feel and shifting performance.
  • Oil Type: GAS GAS recommends NILS Clutch Trial or an equivalent full synthetic oil with suitable additives for wet clutch applications .

Additional Owner Tips

  • Keep a maintenance log to track oil changes by hours and date.
  • Inspect other basic elements while on the stand—look at your chain, sprockets, and check for leaks.
  • If performing regularly in harsh conditions (mud, sand, water crossings), consider shortening your oil change intervals from the manual recommendation.

Doing your own oil changes not only protects your 2021 GAS GAS TXT GP 300 but deepens your understanding of its performance. Stay on top of your maintenance, and your bike will reward you with reliability and control on every ride.

MotoSport.com: Your source for genuine tools, oil, and service parts for your GAS GAS maintenance needs.

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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.