How to Change the Oil in a 2018 Honda CRF125FB – Step-by-Step Guide by MotoSport.com

Shop parts for a 2018 Honda CRF125FB Dirt Bike.

Changing the oil in your 2018 Honda CRF125FB is a straightforward maintenance task that will keep your engine running smoothly and extend the life of your dirt bike. Whether you're a seasoned rider or new to motorcycle maintenance, this guide will walk you through the process, highlight necessary tools, and provide important model-specific tips.

Tools and Materials Needed

  • Honda Pro GN4 Motor Oil, 10W-40 (08C35-A141L01) – 1 liter
  • Oil Drain Pan
  • 17mm Socket and Ratchet (or Box Wrench)
  • Small Funnel – The fill hole is small so a small funnel is highly recommended
  • Clean Rag
  • Measuring Cup (such as Ratio-Rite Cup) – Optional, but helpful to get the exact oil volume

Preparation

  • Warm Up the Engine: Start the bike and let it run for 3-5 minutes. Warm oil flows more freely and will drain more completely from the engine.
  • Turn Off the Engine and Let Cool Slightly: Shut off the bike and allow it to cool for a minute or two to avoid burns during the process.

Draining the Old Oil

  • Locate the Drain Plug: The oil drain plug is on the bottom center of the engine case. The 2018 CRF125FB (including the Big Wheel variant) features an accessible drain plug under a skid plate notch, making access easy without plate removal
    • Use your 17mm socket or wrench to loosen and remove the plug, allowing the used oil to drain into your pan.
  • Let the Oil Drain Completely: Give it several minutes until the flow slows to a drip. This ensures all old oil exits, removing more contaminants.
  • Inspect and Clean the Drain Plug: Wipe the plug with your clean rag. Check the condition of the washer or gasket; replace it if it's worn.

Refitting the Drain Plug

  • Reinstall and Tighten: Once drained, reinstall the drain plug and hand-tighten it first. Use your wrench to finish snugging – do not over-tighten, as this could strip the threads.

Adding New Oil

  • Remove the Filler Cap/Dipstick: Unscrew the filler cap (located on the right-hand side of the engine case).
  • Insert the Funnel: Place your small funnel in the oil fill opening.
  • Add New Oil: Pour in 0.9 liters (1.0 US quart) of 10W-40 motorcycle-specific oil. Be precise, as overfilling can cause leaks or engine issues. (The CRF125FB does not have an oil filter to replace – just oil.)

Checking the Oil Level

  • Replace the Filler Cap and Start the Engine: Lightly thread the dipstick/cap back in but do not screw it tightly. Start the engine and let it idle for 3-5 minutes. This circulates the oil.
  • Let the Bike Rest on Flat Ground: Shut off the engine and wait 2-3 minutes, allowing the oil to settle.
  • Check Oil Level: Remove the dipstick and wipe it clean. Set it back in the hole without screwing it in, then pull it to check oil level. On the CRF125FB, ensure the level is between the hash marks on the dipstick. Add or remove oil as needed. Do not screw the dipstick in for checking – set it on the opening only, as per Honda spec.

Model-Specific Call-Outs

  • No Oil Filter to Replace: The 2018 CRF125FB does not have a replaceable oil filter. Only oil changes are needed for routine maintenance.
  • Be Precise with Oil Volume: Use 0.9 liters (slightly less than one US quart). Overfilling or underfilling can harm performance.
  • Hash Mark Check: Always check oil with the dipstick resting in place, not screwed in; this is specific for small Honda four-strokes like the CRF125FB.

Final Steps

  • Dispose of Old Oil Responsibly: Take your used oil to a recycling center or auto parts store, never dump it in the trash or drain.
  • Double-Check for Leaks: After your first post-change ride, check the drain plug and filler area for any leaks. If you find oil seeping, gently retighten but avoid over-torquing.
  • Record the Service: Note the date and hours/miles to track your next scheduled change.

Rider Tips

  • Regular oil changes (every 10–15 hours of riding for off-road conditions, or as specified in your owner’s manual) will maximize the lifespan and reliability of your Honda CRF125FB.
  • Always use motorcycle-specific oil; auto engine oils may not be compatible with your clutch design.
  • If your riding conditions are especially dusty, muddy, or at high RPM, consider more frequent oil changes.

With this straightforward maintenance routine, your 2018 Honda CRF125FB will provide fun and reliable performance for years. For Honda OEM replacement parts and high-quality oils, trust MotoSport.com for all your dirt bike essentials.

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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.