How to Change the Oil in a 2022 GAS GAS MC 125

Shop parts for a 2022 GAS GAS MC 125 Dirt Bike.

Changing the oil in your 2022 GAS GAS MC 125 is a crucial step for maintaining peak transmission and clutch health. This task is straightforward and can be done at home with basic tools, provided you follow the recommended steps and use the right products. Below, you'll find a proprietary guide by MotoSport.com to safely and effectively change your transmission (gearbox) oil, as the MC 125 uses a separate gearbox oil system instead of shared engine/gear oil like four-strokes.

Tools and Supplies Needed

  • 8mm and 13mm socket or wrench (for drain and filler bolt)
  • Ratcheting wrench or T-handle
  • Oil drain pan
  • Clean rags
  • Funnel (preferably with a small tip for transmission oil fill port)
  • Contact cleaner (for cleaning spill or debris near drain plug)
  • New crush washer (optional but recommended)
  • Gloves (to keep hands clean and for heat protection)
  • Fresh gearbox oil (check owner's manual or bottle, usually 10W-40 or manufacturer-recommended gear oil)

Recommended Oil

  • Transmission/gear oil: 10W-40 motorcycle gear oil or recommended Maxima MTL or similar.
  • Oil quantity: For the 2022 GAS GAS MC 125, refer to your owner's manual–typically 700ml to 750ml but always check the specific model requirement.

Step-by-Step Oil Change Instructions

  • 1. Warm Up the Bike
    • Start the bike and let it idle for a minute or two. This helps the oil become less viscous, allowing for a more complete drain.
  • 2. Secure the Bike
    • Place your GAS GAS MC 125 upright on a stand. Avoid using a stand that blocks access to the drain plug.
  • 3. Remove the Drain Plug
    • Find the oil drain bolt (underneath the right side of the engine case).
    • Place your drain pan underneath and use a 13mm socket to remove the plug carefully.
    • If the brake pedal blocks access, gently move it out of the way. Some users slide a flat-head screwdriver between the pedal and frame to create space, but be gentle to avoid damaging anything

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  • 4. Allow Oil to Drain Completely
    • Tip the bike slightly side-to-side to help residual oil escape. Wait until the oil flow slows to drips.
    • Inspect the drained oil for debris. Small particles are normal, but large metal shavings may indicate internal wear

      .
  • 5. Clean and Reinstall the Drain Plug
    • Wipe the plug clean and check or replace the crush washer.
    • Apply a small amount of fresh oil or anti-seize to the threads if desired.
    • Thread the plug back in by hand to avoid cross-threading, then tighten with your wrench (do not overtighten–check your manual for the correct torque specification).
  • 6. Refill with New Oil
    • Remove the oil fill cap (right crankcase cover) with your 8mm T-handle.
    • Insert a funnel and add the correct volume of new gear oil (usually 700ml–750ml for this bike, but check your owner's manual to confirm).
    • Allow oil to settle for a minute before checking level at the sight glass or the oil check bolt if equipped.
  • 7. Double-Check for Leaks and Oil Level
    • Start the motorcycle and let it idle for a minute. Shut off and check for leaks around the drain and fill plugs.
    • Check oil level again and top off if necessary.
  • 8. Dispose of Used Oil Responsibly
    • Pour the old oil into a sealed container and take it to a recycling center or auto parts store that accepts used oil.

2022 GAS GAS MC 125-Specific Tips and Call-Outs

  • This model uses a two-stroke engine with separate transmission/gearbox oil—do not add engine oil to the fuel tank or crankcase.
  • Gear oil capacity is typically around 700ml–750ml, but you should always verify with your owner's manual for the precise figure.
  • If the brake pedal obstructs drain plug access, move it aside temporarily as described above

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  • Check for signs of water or milky oil, indicating a bad gasket or seal that may require further inspection.
  • Always use a new crush washer if possible to prevent leaks after reassembly.
  • If preferred, you can gently tip the bike side-to-side (or even lay on its side briefly, but only on a soft surface) to fully evacuate old oil.

Final Check and Maintenance Schedule

  • Check oil level after first ride and tighten drain plug if seepage occurs.
  • Record the date and hours of oil change for your maintenance log.
  • Inspect your transmission oil more frequently during the break-in period or after wet or muddy rides.

Regular oil changes extend the life of your GAS GAS MC 125's transmission and clutch. If in doubt, consult your owner's manual or contact your authorized GAS GAS dealer for support. Stay tuned to MotoSport.com for more in-depth dirt bike maintenance tips and expert how-tos.

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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.