How to Change the Oil in a 2013 GAS GAS TXT PRO 125: Step-by-Step Guide

Shop parts for a 2013 GAS GAS TXT PRO 125 Dirt Bike.

Keeping your 2013 GAS GAS TXT PRO 125 running in top condition means regular oil changes are essential. This detailed, MotoSport.com-exclusive guide covers the tools required, step-by-step procedures, and specific call-outs you need to know for this model.

Tools and Materials Needed

  • Oil pan (to catch drained oil)
  • 10mm and 13mm socket or spanner (depending on your drain bolt size, always confirm before starting)
  • Clean funnel
  • Rags or shop towels (for wiping off spills and cleaning surfaces)
  • New gear oil (Quality 75W transmission/gear oil; capacity is approximately 0.58 quarts or 550ml for this model)
  • Gloves (optional but recommended for cleanliness)
  • Torque wrench (optional but recommended, to avoid over-tightening the drain bolt)

Preparation

  • Warm up the dirt bike for 2-3 minutes to thin the oil, making it easier to drain.
  • Ensure the bike is on a level surface and well-secured using a suitable lift stand.
  • Turn off the engine and let it cool slightly, but keep the oil warm for draining.

Step-by-Step: Changing the Oil

  1. Locate the Drain Plug
    • The drain bolt is found on the bottom side of the engine case. Make sure you have the correct size spanner or socket for your model—common error is using the wrong size; double-check before loosening.
  2. Place the Oil Pan
    • Position the oil pan directly beneath the drain bolt to catch all used oil.
  3. Remove the Drain Bolt
    • Carefully loosen and remove the drain bolt using your spanner/socket. Allow oil to drain completely—this may take several minutes for old oil to drip out entirely.
    • Keep an eye out for any washers or O-rings that may come off with the bolt; these must be reinstalled to prevent leaks.
  4. Clean and Inspect Parts
    • Wipe the drain bolt and its seating area free of debris and old oil using a rag.
    • Inspect the bolt and washer; replace if excessively worn to prevent stripping or leaking.
  5. Reinstall the Drain Bolt
    • Screw the drain bolt back in by hand first to avoid cross-threading.
    • Tighten it snugly with the wrench; do not over-tighten, as the aluminum engine case is soft and can strip easily. Use a torque wrench set to the manufacturer's spec if possible.
  6. Add New Oil
    • Locate the oil fill plug on the top of the right side crankcase.
    • Remove the fill plug and insert a clean funnel.
    • Pour in 0.58 quarts (550 ml) of high-quality 75W gear oil or equivalent. Popular oils among enthusiasts include GRO or premium synthetic gear oils.
    • Wipe any oil spills and reinstall the fill plug securely.
  7. Check Oil Level
    • Remove the fill/check bolt as directed in your owner's manual to confirm the oil is at the correct level. Oil should just reach the bottom of the threads; add oil a little at a time if necessary.
  8. Start the Engine – Re-Check
    • Start and idle the bike for 1-2 minutes, then turn off and check for leaks around the drain and fill plugs.
    • Re-check oil level, topping up if required.
  9. Proper Disposal
    • Take your used oil to a recycling center or local auto parts store for safe disposal.

2013 GAS GAS TXT PRO 125: Model-Specific Call-outs

  • Drain Bolt Caution: The engine case on this bike is soft aluminum—be extremely careful not to overtighten the drain bolt to avoid stripping the threads.
  • Oil Type – Capacity: Use a quality 75W gear oil and always measure or use the correct volume (0.58 quarts/550 ml) to avoid under- or overfilling.
  • Washer Attention: Always double-check if the drain plug washer stays with the bolt. Replace it with a new one if it appears worn or flattened to prevent leaks.
  • Periodic Air Filter Check: While you've got the tools out, take a minute to inspect the air filter for cleanliness. This is especially important when riding in dusty environments.
  • Residual Oil: After draining, a small amount of oil may remain in the gearbox—don't keep shaking the bike, as this is normal, and draining completely is not possible.

Additional Maintenance Tips

  • Change oil after every 10-15 hours of riding or as recommended in your owner's manual for maximum protection.
  • Inspect oil for signs of contamination (milky color, metallic flakes) as these may indicate clutch or transmission issues.

Changing your GAS GAS TXT PRO 125's oil is a straightforward job that pays off in performance and longevity. For more dirt bike maintenance tips and parts, trust MotoSport.com for all your dirt bike 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.