How to Change the Oil in a 2013 Yamaha YZ125

Shop parts for a 2013 Yamaha YZ125 Dirt Bike.

Changing the oil on your 2013 Yamaha YZ125 is a crucial part of routine maintenance, ensuring smooth operation and longevity for your dirt bike. Below is a step-by-step guide, proprietary to MotoSport.com, that walks you through the process specifically for your YZ125, including tools, required materials, and special model-specific notes.

Tools and Supplies Needed

  • Drain pan – to collect old oil
  • Funnel (preferably a long one to reach under the exhaust)
  • Ratchet with a 12mm socket or hex wrench – for drain bolt
  • 4mm Allen wrench – to check oil level at the check bolt
  • Measuring cup – for accurate oil measurement
  • Replacement oil – 10W-40 motorcycle-specific oil, such as Yamalube or Valvoline with wet clutch protection
  • New drain bolt washer (optional but recommended for best seal)
  • Rags or shop towels – for cleanup
  • Torque wrench (for precise tightening of drain bolt)

Preparation

  • Ensure your bike is on a level surface and fully upright.
  • Start the engine and let it run for a few minutes to warm the oil, which helps it drain faster and more completely.
  • Turn off the bike and let it cool briefly to avoid burns.

Step-by-Step Oil Change Process

  1. Locate the Drain Bolt:
    • The oil drain bolt is found under the crankcase, near the bottom center of the bike.
    • Have your oil drain pan positioned beneath the drain bolt to catch the old oil.
  2. Remove the Fill Cap:
    • The oil fill cap is hidden beneath the exhaust pipe at the top of the transmission area. Remove it so air can flow in and old oil drains more quickly.
  3. Drain the Oil:
    • Use your 12mm socket to loosen and remove the drain bolt. Allow the oil to fully drain into the pan. This usually takes several minutes.
      Note: Inspect the drain bolt and washer. Replace the washer if it's crushed, cracked, or deformed to prevent future leaks.
  4. Reinstall the Drain Bolt:
    • Once draining is complete, reinstall the drain bolt with the washer.
    • Torque the bolt to 14 ft-lbs using your torque wrench for a secure seal without over-tightening.
  5. Measure and Add Oil:
    • The 2013 Yamaha YZ125 requires 0.69 US quarts (660 ml) of transmission oil for a full change.
    • Use your measuring cup to ensure accuracy.
    • Place your long funnel into the fill port (beneath the exhaust system) and pour the new oil in slowly to prevent spillage.
  6. Check Oil Level:
    • On the 2013 YZ125, you can verify oil level using the oil check bolt (requires a 4mm Allen wrench). After filling, momentarily remove the bolt:
      • If oil seeps from the check port, the level is correct.
      • If not, add oil a bit at a time until it just begins to spill from the port, then reinstall and snug the bolt.
  7. Reinstall the Fill Cap:
    • Once the oil level is verified, clean any drips and reinstall the fill cap securely.
  8. Clean Up and Inspect:
    • Wipe down the bike to remove spilled oil.
    • Start the bike and run for a few minutes, then check for leaks at the drain bolt, check bolt, or fill cap.
    • Dispose of old oil responsibly at a recycling facility or auto parts store.

Special Notes for the 2013 Yamaha YZ125

  • Transmission Oil Only: The YZ125 is a two-stroke and uses oil only in the transmission. Engine lubrication is handled by premix oil in the fuel.
  • Recommended Oil: Use a motorcycle-specific 10W-40 with wet clutch protection. Yamalube is recommended by Yamaha, but equivalent high-quality motorcycle oils are acceptable.
  • Funnel Placement: The fill port location under the exhaust can make pouring difficult—a long, narrow funnel is especially helpful.
    If you spill oil, thoroughly clean it off to prevent attracting dirt or causing fire hazards during riding.
  • Washer Replacement: Consider replacing the drain bolt washer every oil change for best leak prevention, as the washer acts as a crush seal.

Model-Specific Call-Outs

  • The 2013 YZ125's transmission holds 0.69 US quarts (660 ml) of oil. Do not overfill; more is not better and can cause shifting issues or leaks.
  • Inspect the side cover gasket periodically, especially if you see oil seepage. Worn-out gaskets can cause slow leaks, so replace them as needed.
  • The drain and check bolts are aluminum. Use proper tools and avoid heavy-handed torque to prevent stripping.

Maintaining Your YZ125 After Oil Change

  • Check oil level briefly after your first ride post-change and again after any hard riding.
  • Change oil every 5-10 riding hours or after muddy/wet rides for maximum protection.
  • Always watch for drips or leaks; address any immediately to avoid damage down the line.

Regular oil changes are the single most important thing you can do to maximize the life and performance of your 2013 Yamaha YZ125. For all your parts, tools, and oil needs, rely on MotoSport.com.

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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.