How to Change the Oil in a 2005 Honda CR125: Step-by-Step Guide

Shop parts for a 2005 Honda CR125 Dirt Bike.

MotoSport.com brings you a complete, proprietary guide on how to change the oil on your 2005 Honda CR125. This process covers everything you need to know, including the essential tools, recommended oil type, detailed steps, and model-specific notes. Keep your CR125 running strong by following these instructions precisely.

Tools & Materials Needed

  • 10mm and 17mm sockets or wrenches (for oil drain bolt and other hardware)
  • Oil drain pan (to catch old oil)
  • Measuring cup (for accurate oil measurement)
  • New sealing washer (recommended each change)
  • Clean shop rags
  • Funnel
  • Gloves (optional but recommended)
  • Pro Honda HP2 2-stroke oil, mixed 32:1 (for premix)
  • Gear/transmission oil: 0.60 US qt (0.57 L) recommended

Recommended Oil & Specs for 2005 Honda CR125

  • Transmission/Clutch Oil Capacity: 0.60 US qt (0.57 L)
  • Drain Bolt Torque Spec: 21 lbf–ft (29 N–m, 3.0 kgf–m)
  • Oil Check Bolt & Filler Cap Torque: 7 lbf–ft (10 N–m, 1.0 kgf–m)
  • Recommended Oil Brand: Pro Honda HP2 (or equivalent)

Step-by-Step Oil Change Instructions

  • Warm up the engine
    Start the bike and let it idle for about 2–3 minutes. Warming up the transmission oil reduces its viscosity, helping it drain more thoroughly and removing contaminants with it. Shut off the engine and support the bike in an upright position on a level surface.
  • Locate the drain, fill, and check bolts
    • The oil filler cap is found on the right crankcase cover.
    • The drain bolt is on the bottom of the engine (typically 17mm).
    • The oil check bolt is found on the right side of the engine for confirming oil level after refilling.
    These spots are unchanged across CR125 models from the late '90s to 2005, so most years follow this location and method.
  • Remove the drain bolt
    Place your oil catch pan beneath the engine and remove the 17mm drain bolt. Allow the old oil to drain completely—this may take a few minutes. Check that the aluminum sealing washer either comes off with the bolt or stays on the plug; replace it if damaged or crushed. This step prevents leaks and ensures proper sealing during reinstallation.
  • Remove the oil filler cap
    This allows air to enter, facilitating quicker draining.
  • Inspect the oil
    As the oil drains, take note of the appearance. Light gray or metallic shades may indicate normal clutch and gear wear, but heavy debris or metal shavings can be a sign to inspect your clutch and transmission internals.
  • Install new sealing washer and replace drain bolt
    Once drained, fit a new sealing washer on the drain bolt and reinstall it. Torque it to manufacturer spec (21 lbf–ft / 29 N–m).
  • Add new oil
    Using a funnel, pour in the recommended amount of new oil (0.60 US qt or 0.57 L) through the oil filler opening. Use a measuring cup for accuracy.
  • Check oil level
    With the bike upright and level, remove the oil check bolt to ensure oil is at the correct height. If oil seeps from the check bolt opening, the level is correct. If not, add a bit more and check again. Reinstall and torque the check bolt to 7 lbf–ft (10 N–m).
  • Replace the filler cap and tighten to spec.
  • Start and check for leaks
    Start the engine, let it idle for one minute, then shut off and inspect around the drain bolt and filler cap for leaks.
  • Dispose of old oil responsibly
    Take used oil to a local recycling center. Improper disposal is hazardous to the environment.

2005 Honda CR125 Owner Call-Outs

  • The oil system on the CR125 is only for the transmission/clutch side, not the main engine. The main engine is lubricated by 2-stroke premix in the fuel. Never add four-stroke engine oil to the crankcase.
  • Always use the recommended gear oil or high-quality transmission oil for 2-stroke MX bikes to ensure clutch and gear longevity.
  • Re-torque bolts carefully; overtightening may strip aluminum threads.
  • If you notice an abnormal metallic slurry in the oil, inspect clutch or transmission components for early wear.
  • This procedure is standard on 2002–2007 CR125s with minor changes in cosmetics, not mechanics.

Routine Maintenance Tips

  • Change your CR125’s oil every 5–10 engine hours, especially if riding hard or in dirty/muddy conditions.
  • Inspect drain bolt magnet (if equipped) for excess metal debris as an early warning system.

By following this detailed guide, exclusive to MotoSport.com, you can keep your 2005 Honda CR125’s transmission running smoothly and reliably for many seasons of riding.

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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.