How to Change the Oil in a 2023 GAS GAS MC 125: A MotoSport.com Guide

Shop parts for a 2023 GAS GAS MC 125 Dirt Bike.

  • Estimated Time:– 30–45 minutes
  • Difficulty:– Beginner to Intermediate

Tools and Supplies Needed

  • 8mm T-handle wrench
  • 8mm Allen wrench
  • 13mm ratchet or socket
  • Oil drain pan
  • Clean rags or shop towels
  • Torque wrench (capable of at least 15 ft-lb)
  • Needle nose pliers (optional, for oil screen removal and install)
  • Maxima Contact Cleaner or similar (for cleaning parts)
  • Fresh 2-stroke transmission/clutch oil (consult manual for capacity and recommended type)
  • Replacement crush washer(s) and O-rings if needed
  • Bike stand with side/rear access
  • Funnel

Specific Tips for the 2023 GAS GAS MC 125

  • This model uses a case-mounted drain bolt. Use a stand that allows easy access to the bolt underneath.
  • The GAS GAS MC line shares many engine service characteristics with KTM and Husqvarna 2-strokes of the same era, but always consult your 2023 owner's manual for torque specs and oil capacity to avoid mistakes.
  • Never use automotive engine oil; use only dedicated 2-stroke gearbox oil of the recommended viscosity.

Step-by-Step Oil Change Procedure

  1. Warm up the engine briefly:– Start your bike and let it idle for 2–3 minutes. This helps the oil flow better for draining. Shut it off and secure on an appropriate stand so you have clear access underneath.
  2. Remove the oil fill plug:– Unscrew the engine oil fill cap on the right side of the engine. This allows air in as oil drains, improving flow.
  3. Locate and remove the drain bolt:–
    • The MC 125's drain bolt is typically on the bottom side of the crankcase. Place your drain pan under this bolt.
    • Use your 13mm ratchet or socket to remove the bolt. Let the oil fully drain into the pan.
  4. Inspect the oil and the drain bolt:–
    • Look at the old oil. Some very fine metal particles are normal; large pieces or chunks could indicate a mechanical problem.
    • Clean the drain bolt thoroughly. If it uses a crush washer, inspect and replace if needed.
  5. Clean and inspect the oil screen (if equipped):–
    • Some models have an oil screen accessible during an oil change. Remove, clean with parts cleaner, and reinstall with care to avoid damage to O-rings. (Check your manual for location and tips. Use needle nose pliers if access is tight.)
  6. Reinstall the drain bolt:–
    • Hand thread the bolt, then finish tightening with your ratchet.
    • Torque the drain bolt to the spec in your manual (typical is around 14–16 ft-lb for GAS GAS, but always confirm).
  7. Fill with new oil:–
    • Fit the funnel to the fill port.
    • Consult the manual for quantity (usually about 0.7 liters for a 2023 MC 125)
    • Pour in the correct amount of recommended 2-stroke transmission oil.
  8. Check for leaks and finish up:–
    • Wait 1–2 minutes, then check for any oil leaks at the drain bolt.
    • Reinstall the oil fill cap securely.
    • If your bike has an oil level check bolt, remove this briefly to ensure oil has reached the correct level when in the upright position—top off if needed.
    • Wipe away all excess oil from the exterior with a rag.
    • Properly recycle the used oil at an accepted facility.
  9. Start and inspect:– Let the bike idle for 1 minute. Turn it off, check again for leaks, and confirm smooth clutch/gear operation on your next ride.

Best Practices and Extra Advice

  • Change your oil every 5–10 riding hours or after any extreme riding conditions.
  • Never overtighten the drain bolt—it can strip the aluminum casing.
  • Remember to check your clutch feel after each oil change; new oil can subtly change engagement.
  • If your MC 125 feels notchy or harsh when shifting, try changing oil brands or service more frequently.
  • Always keep a fresh crush washer and extra O-rings on hand—they're inexpensive and help prevent drips or leaks.

2023 GAS GAS MC 125 Model-Specific Call Outs

  • The 2023 MC 125 uses a typical 2-stroke "wet clutch" design. Never use friction-modified, automotive oil—always use dedicated 2-stroke/gearbox fluids.
  • Some stands will block access to the drain bolt; use a rear-wheel stand or side stand so you can easily get to the bolt with your tools.
  • Always inspect the thin, replaceable O-rings on the drain and fill caps, as a bad O-ring is a top source of leaks.
  • If you ride in deep water or mud, change oil more often.

Conclusion

  • Changing the oil in your 2023 GAS GAS MC 125 is quick and keeps your clutch and transmission running smoothly.
  • Doing it yourself is rewarding and a great way to spot early signs of wear or problems before they become costly.
  • Be sure to purchase the correct oil and filters from MotoSport.com for the best results and continued performance.

Related Shopping Categories

Shop Motor Oil for a 2023 GAS GAS MC 125 Dirt Bike.

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Shop Oil Drain Pans for a 2023 GAS GAS MC 125 Dirt Bike.

Shop Tools for a 2023 GAS GAS MC 125 Dirt Bike.

Shop Oil Fillers and Drain Plugs for a 2023 GAS GAS MC 125 Dirt Bike.

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.