How to Change the Oil in a 2018 Yamaha YZ450FX: Complete Guide

Shop parts for a 2018 Yamaha YZ450FX Dirt Bike.

Oil changes are the lifeblood of your 2018 Yamaha YZ450FX's engine health and performance. Regular oil and filter changes will keep your four-stroke dirt bike running strong and extend its lifespan. This guide from MotoSport.com covers the specific tools, step-by-step procedure, and pro tips every YZ450FX owner needs to know for flawless oil changes.

Tools and Supplies Needed

  • Socket wrench (with 12mm & 8mm sockets)
  • Torque wrench
  • Oil drain pan
  • Funnel
  • Gloves & rags
  • Flat-blade screwdriver
  • Replacement oil filter (e.g., HiFlo HF140 or OEM)
  • Replacement crush washer (recommended for each oil change)
  • Magnetic drain plug (optional but suggested for extra engine protection)
  • Yamalube 10W-40 or equivalent JASO MA rated oil
  • Copy of your OEM service manual for specifications and torque values

Step-by-Step: Changing the Oil on a YZ450FX

  1. Warm Up the Engine
    Start the bike and let it idle for 2-3 minutes in a well-ventilated area. This thins the oil for a more complete drain.
    Tip: Never change oil with a completely cold engine.
  2. Remove the Skid Plate (if installed)
    Use the socket wrench to detach and set aside any skid plate covering the drain bolt.
  3. Drain the Old Oil
    Place the oil pan under the engine. Use the 12mm socket to remove the drain bolt located at the bottom of the crankcase.
    Ensure you also remove the crush washer; replace it if it's damaged or worn.
  4. Remove and Replace the Oil Filter
    The oil filter is located on the right side of the engine behind a cover secured with 8mm bolts. Remove the bolts, then the cover, and pull out the old filter.
    Inspect and replace the O-ring on the cover if needed.
    Call-out: The HiFlo HF140 is a recommended filter; always ensure it's installed in the correct orientation. Unlike some older models, the YZ450FX's filter housing makes backward installation difficult, but double-check to prevent oil starvation and engine damage (as has happened on older Yamaha and Honda models).
  5. Clean the Oil Strainer
    Unscrew, remove, and inspect the oil strainer. Clean it thoroughly with brake or parts cleaner and reinstall it.
  6. Reinstall Drain Bolt
    Install a new crush washer if possible. Hand-tighten the drain bolt, then torque it to the specification found in your service manual (typically around 17 ft-lbs, but verify for your specific model year).
  7. Add Fresh Oil
    Place the funnel into the fill port. Pour in the oil (typically 1.0 - 1.1 liters for the 2018 YZ450FX, but double-check your manual for exact capacity).
    Use Yamalube 10W-40 or comparable high-quality oil for optimal clutch and engine performance.
  8. Check Oil Level
    Start the engine and let it idle for 1-2 minutes, then shut it off. Wait 1-2 minutes, then check the level via the sight glass. Add oil if needed to reach the correct mark.
  9. Reinstall the Filler Cap and Skid Plate
    Confirm the filler cap is tight, reinstall the skid plate and secure all hardware.
  10. Dispose of Used Oil Responsibly
    Take used oil and the old filter to a recycling center or auto parts store.

Yamaha YZ450FX-Specific Oil Change Tips

  • Oil capacity: Usually 1.0 – 1.1L. Always verify in your owner's manual for the 2018 model, as the YZ450FX uses a slightly different engine case than the WR450F or older YZ models.
  • Magnetic drain plug: Highly recommended, as it helps catch metallic debris and prolongs engine life.
  • Filter orientation: The filter design makes backward installation difficult, but always double-check direction. The open side faces the engine – improper installation on older Yamahas or other brands can be catastrophic.
  • O-rings and washers: Replace as needed with each oil change to prevent leaks and ensure proper sealing.
  • Service interval: Yamaha recommends oil changes after every break-in period and every three races or every 7.5 hours of engine run time — aggressive riders should change more frequently.

Final Checklist

  • Inspect for leaks around the drain plug and filter cover after engine warm-up.
  • Discard rags and shop towels safely.
  • Record the service in your maintenance log.
  • Check oil level again after the first ride and top off if needed.

Keep your 2018 Yamaha YZ450FX performing at its best by staying diligent with regular oil changes and using only high-quality parts and fluids, all available at 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.