How to Change the Oil in a 2018 Yamaha YZ85

Shop parts for a 2018 Yamaha YZ85 Dirt Bike.

Keeping your 2018 Yamaha YZ85 operating at peak performance means regular maintenance, and one of the most crucial tasks is changing the oil. This comprehensive guide from MotoSport.com provides a step-by-step walkthrough, lists all necessary tools, and details important model-specific notes for performing a flawless oil change on your YZ85.

Tools and Supplies Needed

  • 10mm box or socket wrench (for the drain bolt)
  • Oil catch pan
  • Fresh transmission oil (Yamaha recommends the specific type and approximately 500 cc for the 2018 YZ85)
  • Funnel (helps prevent spills)
  • Shop rags or paper towels
  • Protective gloves (recommended for a cleaner job)
  • Torque wrench (if available, to torque the drain bolt to manufacturer specifications)

Important Notes for the 2018 Yamaha YZ85

  • The YZ85 is a two-stroke engine, but it uses separate gear oil for the transmission—this is what you are changing.
  • There are no oil-level check or overflow bolts on the 2018 and newer YZ85s—fill with the exact quantity specified in the manual.
  • The oil drain bolt is located on the right side of the bike, behind the rear brake pedal; look for the copper crush washer to confirm you have the correct bolt.
  • Always warm up the engine for a few minutes prior to draining the oil; this allows the oil to flow out more easily.
  • Replace the copper crush washer if it shows signs of flattening, cracking, or corrosion.

Step-by-Step Instructions

  • Prepare your workspace and bike
    • Start the engine and let it idle for 2 to 3 minutes to warm the oil. Then turn off the bike and place it on a secure stand.
    • Put on your gloves and position the oil catch pan beneath the drain bolt.
  • Remove the drain bolt
    • Use the 10mm wrench to loosen and remove the drain bolt located behind the rear brake pedal.
    • Let all the oil completely drain into the pan. It may help to gently tip the bike slightly to the left to ensure all oil exits the case.
  • Clean and inspect
    • Wipe down any oil residue from the drain bolt and crush washer.
    • Inspect the washer for wear or damage. Replace it if necessary to prevent leaks.
    • Check the drained oil for metal shavings or excessive debris–indicator of possible internal issues.
  • Reinstall the drain bolt
    • Thread the bolt and washer by hand first to prevent cross-threading.
    • Tighten snugly with your wrench. If you have a torque wrench, torque to manufacturer specifications found in your YZ85 manual.
  • Add fresh transmission oil
    • Remove the oil fill cap located on top of the right engine case.
    • Using the funnel, pour in the new oil. For the 2018 YZ85, the correct amount is 500 cc (check your manual for current specs).
    • Do not overfill—there’s no check bolt; going by quantity is critical for this model.
  • Finish up and check for leaks
    • Wipe away any spilled oil. Reinstall the fill cap securely.
    • Start the bike and let it idle for a few moments. Shut off, then check around the drain bolt and case for leaks.
    • Dispose of used oil responsibly at a local recycling center.

Troubleshooting and Additional Tips for the YZ85

  • If the drained oil is milky, it could indicate water contamination; inspect crank seals immediately.
  • Always use oil designed for two-stroke transmission systems to avoid clutch performance issues.
  • Change oil every 5–10 riding hours for optimal performance, or more frequently in severe riding conditions.

Why Proper Oil Changes Matter for Your YZ85

  • Proper oil maintenance extends the life of your clutch and gears, contributes to easier shifting, and preserves overall engine health.
  • Neglecting routine oil changes can lead to excessive transmission wear, costly repairs, and unreliable performance.

For more maintenance tips or to find the right transmission oil for your 2018 Yamaha YZ85, visit MotoSport.com or consult your owner's manual. Keeping up with regular maintenance ensures you're always ready for race day or weekend rides.

This guide was written specifically for MotoSport.com and is not to be reproduced without permission.

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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.