How to Change the Oil in a 2022 Yamaha YZ125X: A Complete Step-by-Step Guide

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Keeping your 2022 Yamaha YZ125X in peak performance requires regular maintenance, and changing the transmission (gearbox) oil is one of the most essential tasks. Routine oil changes ensure smooth shifts, protect against wear, and extend the life of your dirt bike. This MotoSport.com proprietary guide walks you through the process with all the model-specific details, tools, and tips you need for a hassle-free oil change.

Tools and Supplies You'll Need

  • 12mm socket and ratchet – for the oil drain bolt
  • 4mm Allen wrench – for the oil level/check bolt
  • Drain pan – to catch old oil
  • Paper towels or rags – for cleanup and to handle messes
  • Funnel – especially a long one, to avoid spills around the exhaust
  • Measuring cup
  • Replacement oil – 10W40 motorcycle oil (meets wet clutch specs)
  • New crush washer (recommended) – for the drain bolt

Model-Specific Notes for the 2022 YZ125X

  • Oil Capacity: 0.69 US quarts (660 milliliters) of 10W40 oil
  • Be sure the bike is upright and level when checking or filling the oil
  • Torque Spec for drain bolt: 14 foot-pounds (do not overtighten.)
  • Always replace the crush washer on the drain bolt if possible for a proper seal

Step-by-Step Oil Change Instructions

  • Warm up the engine.
    • Start your bike and let it run for a few minutes. Warm oil drains faster and more completely, carrying debris with it.
  • Stabilize the bike.
    • Place the YZ125X on a center stand or lift so it’s upright and level.
  • Locate the drain bolt.
    • The drain bolt is a 12mm bolt found under the right side of the crankcase.
  • Position your drain pan.
    • Place it so it will catch all the old oil.
  • Remove the drain bolt.
    • Use a 12mm socket and ratchet.
    • Careful, the oil may be hot.
    • Remove and set aside the old crush washer.
    • Let all oil drain completely – be patient.
  • Inspect and replace drain bolt washer.
    • Install a new crush washer on the drain bolt. This helps prevent leaks and acts as a torque cushion.
  • Reinstall the drain bolt.
    • Tighten with your 12mm socket until the washer just compresses or to 14 ft-lbs.
  • Remove the fill cap.
    • It’s located on the top of the right side crankcase.
  • Pour in fresh oil.
    • Measure 0.69 quarts (660 ml) of 10W40 motorcycle oil.
    • With a funnel, slowly pour the oil into the fill port.
  • Check the oil level.
    • There’s a check bolt (oil level bolt) on the right side of the crankcase. Use a 4mm Allen wrench to remove it.
    • With the bike upright, a little oil should trickle from the check bolt hole when the level is correct.
    • If no oil comes out, add oil in small amounts until it does.
    • Reinstall and tighten the check bolt gently.
  • Replace the fill cap and tidy up.
  • Start the engine and check for leaks.
    • Run the bike for a few minutes. Inspect the drain bolt and crankcase for leaks. If you spot any, shut off the engine and correct as necessary.
  • Dispose of old oil responsibly.
    • Bring it to a recycling center or auto parts store that accepts used oil.

Owner’s Call-Outs for the 2022 YZ125X

  • Always use oil formulated for wet clutches and two-stroke transmissions to protect your clutch and gearbox.
  • Replace the drain bolt washer with every change to avoid leaks and prevent over-torquing damage.
  • Double-check torque and level – overtightening can strip threads, and running low on oil can quickly ruin a high-revving two-stroke engine.
  • Oil level check is easy – remove the check bolt with a 4mm Allen and top up until oil trickles out with the machine level.

Keep your engine’s heart healthy by changing the gearbox oil every 5–10 hours of riding (or sooner if you race or ride in harsh conditions). For more model-specific maintenance guides, parts, or oil, visit MotoSport.com—your partner for everything dirt bike.

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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.