How to Change the Oil in a 2021 Husqvarna TC125: A Step-by-Step Guide

Shop parts for a 2021 Husqvarna TC125 Dirt Bike.

If you own a 2021 Husqvarna TC125, routine oil changes are critical to keeping your dirt bike’s engine running at peak performance. This guide, proprietary to MotoSport.com, will walk you through every step, including model-specific tips, tools required, special callouts, and important reminders. Proper oil changes will not only boost reliability but also extend your engine’s life.

Tools and Supplies Needed

  • 13mm box-end wrench or socket (for drain plug removal)
  • Drain pan
  • Measuring cup (for oil)
  • Clean rags
  • Fresh engine oil (800ml or 0.85 quarts gear oil recommended for TC125)
  • New crush washer or seal ring for drain plug
  • Torque wrench
  • Parts cleaner or brake cleaner (optional, for cleaning)
  • Gloves (optional, for cleanliness)

Prep and Safety

  • Work in a well-ventilated area with the bike on a stand, ensuring it is upright.
  • Start the engine and let it run for 3–5 minutes to warm the oil. Warm oil drains more thoroughly and brings any contaminants with it.
  • Switch the bike off and allow it to cool just enough to avoid burns.

Step-by-Step: Oil Change Process

  1. Remove the Skid Plate (if installed):
    • If your TC125 has a skid plate, remove it for easier access to the drain plug.
  2. Locate and Remove the Drain Plug:
    • The drain plug is on the bottom of the engine. Place the drain pan directly underneath.
    • Use the 13mm wrench to loosen and remove the drain plug.
    • Be cautious; oil will be hot and can drain quickly. Allow it to drain fully — this may take a few minutes.
    • Remove the oil fill cap (located above on the engine case) to allow better oil drainage.
  3. Inspect and Clean Components:
    • Check the drain plug for metal shavings. A small amount is normal, but if you see an excessive amount, consider inspection by a tech.
    • If your model uses an oil screen, remove and clean it with parts cleaner. Spray off any debris or metal shavings and allow it to dry.
      Tip: Make sure the oil screen is properly reinstalled to avoid bypassing filtration.
    • Inspect the crush washer/seal ring. Always replace it to prevent leaks.
  4. Reinstall the Drain Plug and Screen:
    • Make sure contact surfaces are clean and dry before reinstalling.
    • Insert a new crush washer/seal ring onto the drain plug.
    • Tighten the drain plug to factory torque spec: 14.8 foot-pounds (20 Nm) for Husqvarna TC125.
    • If removed, reinstall the cleaned oil screen, making sure it sits in its groove and both O-rings are lubricated and undamaged.
  5. Refill with Fresh Oil:
    • Using a measuring cup, fill 800ml (0.85 quarts) of high-quality 2-stroke gear oil, as recommended by Husqvarna.
    • Pour oil slowly into the fill cap opening to prevent spills. Reinstall the oil fill cap and tighten securely.
  6. Final Checks:
    • With the bike upright, check for any leaks around the drain plug and oil filter area.
    • Start the engine and let it idle for –1 minute, then shut it off.
    • Re-check the oil level (using the level window or check bolt if equipped) and top off as needed.
    • Properly dispose of old oil at a recycling facility.

2021 Husqvarna TC125: Model-Specific Callouts

  • The TC125 uses a separate transmission/gear oil system from the 2-stroke premix system; never mix or substitute oils.
    Gear oil capacity for this bike is 800ml (or 0.85 quarts).
  • Always replace the crush washer/seal ring each oil change to prevent leaks.
  • Inspect the oil screen and O-rings every time; damaged O-rings must be replaced to avoid bypassing filtration and causing transmission damage.
  • While tightening the drain plug, it’s critical to follow the torque spec (14.8 foot-pounds), as overtightening can strip the threads in the aluminum case.
  • If you operate in sandy or muddy conditions, change your oil more frequently for best protection.

Expert Tips for Long Engine Life

  • Warm oil drains more completely and reduces contamination risk.
  • Use only manufacturer-recommended gear oil types for this model.
  • Visually inspect old oil for signs of excessive wear — excessive metallic particles, grey color, or burnt smell may indicate transmission problems.
  • Keep a maintenance log with oil change intervals and observations.

Proper oil changes are among the most valuable maintenance tasks you can do for your 2021 Husqvarna TC125. By following these steps and keeping up with regular maintenance, you’ll ensure smooth shifting, reliable performance, and confidence every time you ride.

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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.