How to Change the Oil in a 2020 Yamaha TTR125L

Shop parts for a 2020 Yamaha TTR125L Dirt Bike.

A regular oil change is essential for keeping your 2020 Yamaha TTR125L running smoothly, prolonging the engine’s life, and ensuring top performance. Yamaha has designed the TTR125 series to make the oil change process straightforward—perfect for the home mechanic. Here’s your in-depth, proprietary MotoSport.com guide for changing the oil on this reliable dirt bike.

Tools and Supplies Needed

  • 10mm or 12mm socket/wrench (check your specific drain bolt size)
  • Oil catch pan
  • Funnel
  • Shop rags or paper towels
  • Replacement oil (Yamaha recommends Yamalube 4-stroke, viscosity 10W-40; check the owner’s manual for confirmation)
  • New drain bolt washer/gasket (recommended for each change)
  • Gloves (optional, but keeps things clean)

Preparation

  • Warm up the engine for a few minutes to help the oil drain smoothly and carry away more contaminants. Let it idle in a well-ventilated area until the crankcase cover is warm to the touch. This also helps to suspend any debris in the oil so it drains with the oil flow. Check for obvious oil leaks while the engine is running–fix these before proceeding.
  • Turn the engine off and park the bike on its side stand or have someone hold it upright once you’re ready to drain the oil.

Step-by-Step Oil Change Process

  1. Locate the drain bolt.
    • The drain bolt is located on the left side of the engine, near the footpeg area and close to the “waffles” on the case. This is your primary drain bolt for the TTR125 series, including the 2020 model. No auxiliary drain bolts required.
  2. Position the oil catch pan.
    • Slide the pan beneath the drain bolt to catch all the old oil as it drains. Positioning it slightly to the back edge helps avoid spills.
  3. Remove the oil fill cap and drain bolt.
    • First, unscrew the oil filler cap (on top of the engine) to prevent a vacuum and allow oil to drain quickly. Then, using your socket or wrench, loosen and remove the drain bolt and its copper washer/gasket. Be careful as oil may start flowing as soon as you break it loose. Let the oil flow out completely. It helps that the bike leans left if parked on the kickstand, encouraging complete drainage.
  4. Optional: Turn the engine over a few times.
    • With the bike in neutral, gently kick the engine over by hand (no starting required) a couple of times to help drain any oil stuck in passages.
  5. Inspect and replace the drain bolt washer.
    • Replace the washer/gasket with a new OEM part to help prevent oil leaks.
  6. Reinstall the drain bolt.
    • Screw in the drain bolt by hand first to avoid cross-threading. Once hand-tight, use the wrench to snug it securely—do not overtighten. Yamaha drain bolts do not require excessive torque and overtightening can strip threads.
  7. Refill with new oil.
    • With the bike upright (ideally, have a second person hold it straight or use a stand), insert a funnel into the fill hole.
    • Pour in the recommended oil volume (typically around 1.0 liter; confirm with your owner’s manual or refer to the oil capacity etched on the crankcase). Replace the oil fill cap when done.
  8. Check oil level.
    • Start the bike and let it idle for a minute to circulate oil. Turn the bike off, wait a couple of minutes, then check the level:
      • Remove the dipstick, wipe clean, reinsert without screwing in, and check the oil level.
      • Ensure oil is between the minimum and maximum dipstick marks. Add oil if necessary, but avoid overfilling.
  9. Dispose of oil properly.
    • Pour old oil into a sealed container and take it to a recycling center or auto parts store that accepts used oil. Never dump motor oil on the ground or down a drain.

Special Call-Outs for the 2020 Yamaha TTR125L

  • This model does not use a traditional replaceable oil filter, but it does have an internal oil screen in the engine. Yamaha does not require regular oil screen service with each change, but checking/cleaning at longer maintenance intervals is wise (consult your manual for details).
  • The recommended oil specification is 10W-40 Yamalube or equivalent four-stroke motorcycle oil.
  • Torque spec for the drain bolt varies by source, but always err on the side of caution and avoid overtightening; “just snug” is typically enough.
  • Engine oil capacity may be labeled on the left engine case–Yamaha frequently prints this spec on their engines for easy access.
  • All Yamaha TTR125 models, including the L and LE, follow the same basic oil change steps. If in doubt, consult your owner's manual for confirmation.

Maintenance Tips

  • Change the oil after the break-in period for a new bike, then every 10-15 hours of use or at least once a season for recreational riders.
  • Always use motorcycle-specific oil; automotive oil is not formulated for wet clutches.
  • Inspect the oil for signs of metal flakes or excessive contamination; consistent contamination can signal internal wear.

Changing the oil on your 2020 Yamaha TTR125L is a simple DIY project that delivers huge long-term benefits. Keep your TTR running strong and enjoy every ride—brought to you by 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.