How to Change the Oil in a 2017 GAS GAS TXT PRO RACING 125

Shop parts for a 2017 GAS GAS TXT PRO RACING 125 Dirt Bike.

Changing the oil in your 2017 GAS GAS TXT PRO RACING 125 is one of the most important maintenance tasks to keep your dirt bike running smooth and prolong the life of its engine and transmission. This comprehensive guide, exclusive to MotoSport.com, walks you through the process step-by-step, with call-outs unique to this model year.

Tools & Supplies Needed

  • Socket set (typically 8mm, 10mm, or 13mm depending on your drain bolt)
  • Box-End or Open-End Wrenches (check bolt size before starting)
  • Oil catch pan
  • Clean rags
  • Funnel (with small spout for filling transmission)
  • Replacement crush washer for drain plug (optional, recommended)
  • New transmission oil (synthetic or semi-synthetic 2-stroke transmission oil, see recommendations below)
  • Cleaning brush (for dirt and debris near fill and drain areas)
  • Latex or nitrile gloves (for keeping your hands clean)
  • Torque wrench (to ensure correct reinstallation of drain bolt, optional but recommended)

2017 GAS GAS TXT PRO RACING 125 – Oil Change Specifics

  • Engine type: 2-stroke, uses pre-mix for the combustion side, but has a separate transmission with its own oil.
  • Transmission oil capacity: Approximately 0.42 quarts (about 400 ml is typical for GAS GAS TXT models). Always check your owner’s manual to confirm.
  • Oil type recommendation: High-quality synthetic or semi-synthetic gear oil, roughly 75W or 80W for optimal clutch performance and gear protection. Brands like GRO and Motul are frequently used in trials communities

    .
  • Drain plug location: Right side, lower section of engine case. Plug can sometimes be hidden by frame rails or bash plates, so have a flashlight ready if needed.

Step-by-Step Oil Change Procedure

  1. Warm up the engine
    Let the bike idle for 3–5 minutes. Warming the transmission oil thins it, making it easier to remove impurities and dirt when draining.
    Note: Always perform this in a well-ventilated area.
  2. Turn off the engine and secure the bike
    Put the bike on a center stand or stable lift so it is perfectly upright.
  3. Locate and remove the drain plug
    Identify the drain bolt under the transmission case. Clean around it to prevent dirt from falling in. Position your drain pan beneath. Use the correct socket or wrench to loosen and remove the drain plug. Allow all oil to fully drain.
    Tip: Go gently when removing and re-installing the drain plug. Thread damage or over-tightening is a common mistake. GAS GAS engine cases are aluminum and can strip easily.
    Watch for: Small aluminum washers on the drain bolt—replace if crushed or deformed.
  4. Inspect old oil and plug
    Look for metal shavings, dark color, or an odd smell—these can signal internal wear. Clean the drain plug and fit a new washer if needed.
  5. Reinstall drain plug
    Once oil is fully drained, reinstall the plug by hand, then gently tighten with a wrench. Refer to your owner's manual for the recommended torque spec (commonly around 10–15 Nm for many GAS GAS models). Do not overtighten.
  6. Fill with new oil
    Find the oil fill cap (right-side engine case, usually plastic or metal with “Oil” indicated). Remove it, insert a small funnel, and add the exact quantity (about 0.42 quarts or 400 ml). Give time for viscous oil to settle. Replace and tighten the cap.
  7. Let oil settle and check level
    Start the bike and let it idle for about a minute, then shut down. Wait a few minutes to allow oil to settle. If your bike has an oil sight glass, check the level—add more if necessary, but do not overfill.
  8. Inspect for leaks
    Wipe down the area around the drain plug and oil fill after the bike is run. Confirm there are no slow leaks.
  9. Proper disposal
    Used oil is harmful to the environment. Pour spent oil into a sealable container and drop it off at an authorized recycling or waste facility.
  10. Record the service
    Log the oil change date and hours/miles on the bike to keep up with your maintenance intervals (every 20–30 hours is a good rule for trials bikes unless ridden in extreme conditions).

Model-Specific Advice and Callouts

  • Engine oil versus transmission oil: The 2017 GAS GAS TXT PRO 125 is a 2-stroke. The engine uses a pre-mix of oil in the gasoline for the combustion process; engine oil changes are not needed, but transmission oil must be replaced regularly for proper clutch and gear function.
  • Oil capacity and sight window: The transmission side uses about 0.42 quarts or 400 ml; it is crucial not to overfill since excess oil can cause poor clutch performance or leaks. Fill until you see the correct level in the oil sight glass or check the dipstick (if equipped).
  • Transmission oil type: GAS GAS recommends a high-quality 75W or 80W gear oil, either synthetic or semi-synthetic for smoother shifts and longer clutch life

    .
  • Transmission system: This generation uses a 6-speed transmission with wet clutch. Incorrect oil type or contaminated oil can quickly affect clutch feel and lifespan.
  • Drain tool recommendation: An oil drain tool or hose can help prevent mess, especially as the drain plug sits close to frame rails on GAS GAS TXT engines

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  • Warm-up reminder: Always warm the engine before draining, as cold oil traps more debris and drains slowly.
  • Avoid over-tightening: GAS GAS drain plugs are known for sensitive threads; tighten only to the specified torque.

Conclusion

Follow this detailed MotoSport.com guide to keep your 2017 GAS GAS TXT PRO RACING 125 performing at its peak and to ensure long clutch and transmission life. Regular and correct oil changes help you get the most out of every ride, wherever your trails take you.

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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.