How to Change the Oil in a 2019 Yamaha YZ85

Shop parts for a 2019 Yamaha YZ85 Dirt Bike.

Regularly changing the oil in your 2019 Yamaha YZ85 is essential to keep your 2-stroke dirt bike performing at its best. The process is quick, straightforward, and a vital part of routine maintenance. MotoSport.com has put together this step-by-step proprietary guide just for YZ85 riders, outlining the exact tools, specifications, and model-specific call-outs you'll need for a flawless oil change every time.

Tools & Supplies Needed

  • 10 mm socket or box-end wrench
  • Socket wrench or ratchet
  • Torque wrench (capable of 10 Nm)
  • Drain pan (for old oil)
  • Rags or paper towels
  • Rubber gloves (recommended but optional)
  • New transmission/gear oil (see note below for correct type and amount)
  • Funnel (optional, makes pouring easier)

Oil Specifications for 2019 Yamaha YZ85

  • Oil capacity:– 500cc (or 500 mL)
  • Recommended oil:– High-quality 2-stroke gear/transmission oil (Motul Trans Oil and others are commonly used)
  • Torque spec for drain bolt:– 10 Nm (always verify in your owner’s manual if unsure)

Steps to Change the Oil

  1. Preparation
    • Start with a clean bike—cleaning any dirt around the engine prevents debris from entering the crankcase during the oil change.
    • Warm up the engine for a few minutes to allow the oil to flow out easily (optional but recommended).
    • Put the bike on a stand or a level surface to ensure accurate drainage.
  2. Locate the Oil Drain Bolt
    • The drain bolt is located on the right side of the engine, just behind the rear brake pedal.
    • Directly below the motor, locate the bolt with a copper crush washer–this is your oil drain plug.
  3. Drain the Old Oil
    • Put on gloves to keep your hands clean.
    • Place your drain pan underneath the engine.
    • Using a 10 mm wrench, loosen and remove the drain bolt. Let the oil drain completely (this may take a few minutes).
    • Remove the fill plug (top of the right engine case) to speed up drainage by releasing vacuum pressure.
  4. Inspect and Clean the Drain Bolt
    • Clean the drain bolt and its copper washer with a rag to remove debris or old oil buildup.
    • Check the washer for signs of wear or damage. Replace if necessary.
  5. Reinstall the Drain Bolt
    • Reinstall the bolt by hand to avoid cross-threading.
    • Use a torque wrench to tighten the drain bolt to 10 Nm (7.4 ft-lb), per Yamaha’s spec for the YZ85.
  6. Add New Oil
    • Pour 500cc (500 mL) of your chosen transmission/gear oil into the fill hole.
    • A funnel can help prevent spills, especially in the tight area around the engine case.
    • Double check the exact amount in your owner’s manual if you have any doubt; over- or under-filling can harm the transmission.
    • Replace the fill plug securely.
  7. Final Check
    • Wipe down any spilled oil and make sure both the drain and fill bolts are tight.
    • Start the engine and let it idle for a minute. Check for any leaks around the drain bolt.
    • Dispose of the used oil at a local recycling center or auto parts store.

2019 Yamaha YZ85 Model-Specific Call-Outs

  • Unlike older or other 2-stroke engines, the YZ85 does NOT have a sight glass or check bolt for oil level. The correct practice is to measure in the specified amount (500 mL) and trust the manufacturer’s fill recommendation.
  • Copper crush washers should be replaced periodically to ensure a leak-free seal.
  • Always check bolt torque specs in your owner’s manual with each oil change, as different years may have small variations.
  • Only use transmission-specific oil for 2-stroke gearboxes; never fill with engine oil or pre-mix oil.

Pro Tips from MotoSport.com

  • Keep a maintenance log and record each oil change date and hours on the bike for optimal service intervals.
  • Pre-warming the engine helps suspend particles in the oil, ensuring you drain out as much debris as possible.
  • Use high-quality transmission oil like Motul Trans Oil, as longevity and shifting feel will be better.
  • If you ride in extreme conditions (wet, muddy, heavy clutch use), change your gearbox oil more frequently.

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Shop Oil Fillers and Drain Plugs for a 2019 Yamaha YZ85 Dirt Bike.

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.