How to Change the Oil in a 2018 Honda CRF125F

Shop parts for a 2018 Honda CRF125F Dirt Bike.

This step-by-step guide is tailored for owners of the 2018 Honda CRF125F dirt bike and is proprietary to MotoSport.com. It covers the essential tools required, full directions for a successful oil change, and specific model notes to ensure peak performance and long-term reliability of your CRF125F.

Tools & Supplies Needed

  • Honda Pro GN4 Motor Oil 10W-40 (part #08C35-A141L01), or any quality 10W-40 or 10W-30 motorcycle-specific oil
  • Oil measuring cup or container (capacity: 1 liter)
  • Oil drain pan
  • 17mm socket and ratchet (a deep socket or an extension helps)
  • Narrow funnel
  • Clean rags or paper towels
  • Gloves (optional, but recommended)

2018 Honda CRF125F Model-Specific Call-Outs

  • No oil filter: The 2018 CRF125F does not use a traditional oil filter—just a screen inside the engine. Frequent oil changes are the best way to maintain cleanliness and longevity for this engine. Do not look for or replace an oil filter on this model.
  • Oil capacity: Fill with 0.9 liters (approx. 1 US quart or 0.8 Imperial quart) of oil when performing a standard oil change.

  • Drain plug location: The drain bolt is at the center bottom of the engine—accessible through a notch in the skid plate (no need to remove the plate). Use a 17mm socket.

  • Make sure the bike is on level ground and stood upright (not on the side stand) when checking or filling oil. Use the dipstick for accurate measurement—but do not screw in the dipstick when checking the oil level; just rest it on the threads.

Step-by-Step Oil Change Instructions

  1. Warm up the engine.
    • Start your 2018 Honda CRF125F and let it idle for 3–5 minutes. Warm oil thins out, making it easier to drain and helping more contaminants leave the engine. Shut off the bike and let it cool for a moment so the oil isn’t scalding but is still warm.

  2. Position your supplies.
    • Place the bike on a level surface using a stand to keep it upright.
    • Put the drain pan under the engine, directly below the drain plug opening.
  3. Remove the drain plug.
    • Using your 17mm socket and ratchet (possibly with an extension), locate the drain bolt under the engine toward the center—visible through the skid plate’s notch. Turn counterclockwise to fully unscrew the plug, being careful as it will likely be warm. Allow the oil to drain completely into your pan.

    • Inspect the crush washer on the drain plug. If it’s severely flattened or damaged, replace it to prevent leaks.
    • Once the oil flow slows to drips, wipe any grime or old oil off the drain bolt and threads on the engine.
  4. Reinstall the drain plug.
    • Thread by hand to avoid cross-threading, then tighten with the ratchet snugly—but don’t overtighten (approx. 18–19 ft-lbs is typical).
    • Wipe away any stray oil with a clean rag.
  5. Refill with fresh oil.
    • Remove the oil filler cap (right side of the engine).
    • Using a narrow funnel, pour in 0.9 liters of new oil (use a quality motorcycle oil rated 10W-40; GN4 is Honda’s recommendation, but 10W-30 is also acceptable).

  6. Check the oil level (IMPORTANT CRF125F procedure).
    • Insert the dipstick back into the filler hole without screwing it down. Remove and check the level—it should be right at the full mark.

    • If necessary, add small increments of oil, rechecking until the oil level is correct.
  7. Run the engine briefly and do a final check.
    • Start the engine and let it idle for 3–5 minutes to let the oil circulate.
    • Shut off the engine and let the bike rest for 2–3 minutes. Check the oil level again using the same dipstick procedure and top off if needed. Check underneath for any signs of leaks around the drain plug.

  8. Dispose of old oil responsibly.
    • Take your used oil to a recycling center, automotive shop, or hazardous waste site.

Extra Pro Tips for the 2018 CRF125F Owner

  • Change your oil every 10 hours of riding or at least once per season—even more often if riding in dusty or harsh conditions.

  • Always use oil formulated for motorcycle wet clutches to ensure proper clutch operation and engine longevity.
  • The absence of a replaceable filter means regular oil changes are doubly crucial.
  • The engine has an internal oil screen. For standard service, simply do the oil drain/fill as above; only clean the oil screen during major disassembly as directed in the service manual.

Common Mistakes to Avoid

  • Screwing in the dipstick while checking the oil level: Rest the dipstick on the threads but do not screw it in; this provides a correct reading for this model.

  • Overfilling: Always pour under the recommended capacity first and check the level—add more only as needed.
  • Skipping oil changes due to lack of a filter: Dirty oil is worse for this model than most; stick to your maintenance intervals.

With the above steps, performing an oil change on your 2018 Honda CRF125F is fast, simple, and ensures your bike stays ready for every ride. MotoSport.com recommends keeping a maintenance log and using only the best products for the longevity of your dirt bike.

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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.