How to Change the Oil in a 2019 KTM 85SX: Complete Step-by-Step Guide

Shop parts for a 2019 KTM 85SX Dirt Bike.

Regular oil changes are essential to keeping your 2019 KTM 85SX in top running condition. This guide, proprietary to MotoSport.com, will walk you through all the steps, tools, and unique requirements you need to know for this specific bike. Read carefully, as using the correct oil type and following all steps is crucial for performance and engine longevity.

Tools and Materials Needed

  • 17mm socket or wrench (for drain plug)
  • 8mm socket or wrench (for oil level/check bolt)
  • Socket wrench
  • Drain pan
  • Measuring cup or beaker
  • Funnel
  • New crush washer (recommended)
  • Lint-free rag
  • 500ml of full-synthetic gear oil (Motorex or Amsoil recommended)
  • Optional: Gloves, bike stand

Before You Start

  • Always work on a cool engine to prevent burns.
  • The oil capacity is 500ml (milliliters).
  • Only use full-synthetic gear oil. Motorex and Amsoil are highly recommended for the KTM 85SX. Do not use cheap or non-synthetic oils, as they do not provide adequate protection for these high-revving engines  .
  • Changing interval: Recommended every 6,000 km, or more frequently under hard racing or off-road conditions  .

Step-by-Step Oil Change Instructions

  1. Warm up the Engine (Optional, but Recommended)
    Briefly start the bike and let it idle for about two minutes. This helps thin the oil so it drains more completely. Shut the engine off and place your KTM 85SX upright on a stand.
  2. Locate the Drain Plug and Oil Level Check Bolt
    The drain plug is the large bolt located directly beneath the engine, behind or below the brake lever area  .
    The oil level/check bolt is on the right side of the case (a small bolt near the clutch cover).
  3. Remove the Oil Level/Check Bolt
    Using your 8mm wrench, loosen and remove the oil level/check bolt. This will help oil drain faster by allowing air to enter the case.
  4. Drain the Oil
    Place your drain pan under the drain plug. With the 17mm wrench, carefully loosen and remove the drain plug. Allow all oil to fully drain out. Inspect the old oil for any metal shavings or debris, which could indicate internal wear.
  5. Clean and Replace the Drain Plug
    Wipe the plug clean. Replace the crush washer if needed for a proper seal. Reinstall the plug and tighten to manufacturer's recommended torque specification (do not overtighten).
  6. Add Fresh Gear Oil
    Insert your funnel into the fill hole and pour in exactly 500ml of full-synthetic gear oil  . Using a measuring cup ensures absolute accuracy and protects your clutch/transmission.
    Tip: It’s preferable to pour a little less at first, then check the level and add more if needed.
  7. Checking and Adjusting Oil Level
    With the bike vertical and on level ground, the oil should just reach the bottom edge of the oil level/check hole.
    • If oil drips out of the check hole, allow it to finish draining—this means it's overfilled (drain off excess).
    • If no oil is visible, add a small amount and repeat the process until it's correct.  
    Reinstall the oil level/check bolt.
  8. Start the Bike and Re-Check
    Start your bike and let it idle for a minute, then shut it down and let it sit for a few minutes. Check for leaks around the drain and check bolt. Repeat the level check one final time to make sure everything is perfect.

Special Model-Specific Tips for the 2019 KTM 85SX

  • Only use full-synthetic oil. This is not negotiable for this high-performance two-stroke gearbox.  
  • Capacity is precisely 500ml of gear oil. Overfilling or underfilling can cause shifting issues or rapid clutch wear.  
  • Regular checks are especially important if ridden in mud, sand, or in racing conditions—change the oil after every 2–3 races if riding aggressively.
  • The KTM 85SX shares transmission design with Husqvarna TC 85 and GasGas MC 85, so procedures (and quantities) are identical  .
  • Oil checking process: The oil level screw is the only way to verify precise fill. It's important to let oil settle for a couple of minutes for a reliable reading  .

Disposal and Final Steps

  • Dispose of used oil properly at a local recycling center.
  • Keep detailed maintenance records for better resale value and peace of mind.
  • Recheck your bolts after your first ride to ensure nothing has loosened due to vibration.

Proper oil changes are straightforward on the 2019 KTM 85SX, but demand care, correct oil choice, and attention to detail. Following this guide ensures optimal transmission performance and extended engine life. For more exclusive tech tips and parts, always choose 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.