How to Change the Oil in a 1978 Honda CR250: MotoSport.com Proprietary Guide

Shop parts for a 1978 Honda CR250 Dirt Bike.

Changing the oil in your 1978 Honda CR250 is essential maintenance that keeps your transmission and clutch operating at their best. This step-by-step guide, proprietary to MotoSport.com, will walk you through everything you need to know for this classic two-stroke dirt bike, including the tools required, detailed instructions, and specific call-outs for your vintage model.

Tools and Materials You'll Need

  • Oil drain pan
  • Socket wrench (typically 17mm for drain bolt, check your bike's specs)
  • Ratchet and extension (optional)
  • Funnel
  • New transmission oil (SAE 10W-40 or equivalent)
  • Measuring cup or Ratio Rite
  • Cleaning rag
  • New sealing washer/crush washer (recommended when reinstalling drain bolt)
  • Rubber gloves (to keep your hands clean and safe)

Recommended Oil Type and Quantity

  • 1978 Honda CR250 uses transmission/gear oil only. The engine is lubricated by premix fuel (usually 32:1 ratio) and does not require a separate engine oil change.
  • Transmission oil capacity:– Approx. 650-700 ml (~0.69 US qt), but always check your owner's manual or local dealer for confirmation.
  • Recommended Oil:– High-quality SAE 10W-40 motorcycle gear oil or Maxima MTL Transmission Lube.

Preparation Steps

  • Warm up the engine for 3 minutes to thin the oil so it drains more completely.
  • Turn off the engine, then safely support the bike in an upright position using a center stand or bike lift.
  • Make sure your work surface is level to ensure accurate oil drainage and filling.

Step-by-Step Oil Change Procedure

  1. Remove the Filler Cap
    • Locate and unscrew the oil filler cap on the right-side crankcase cover. This allows oil to drain more efficiently and later aids in refilling.
  2. Drain the Old Oil
    • Position the oil drain pan under the engine drain bolt.
    • Use your socket wrench to loosen and remove the drain bolt located on the bottom or side of the crankcase.
    • Let the old oil fully drain into the pan. Allow several minutes for a complete drain.
    • Inspect the drain bolt and magnetic tip (if present) for metal shavings—a common reality in older bikes, though excessive shavings may indicate wear.
  3. Replace the Drain Bolt
    • Clean the bolt and install a new crush washer or sealing washer for a secure fit and no leaks.
    • Hand-tighten the drain bolt, then torque with your wrench. For modern CR250Rs, torque is about 21 lbfft (29 Nm), but for a 1978 model you may need slightly less (check your manual if possible; as a guideline, do not overtighten to avoid stripping).
  4. Add New Transmission Oil
    • Use a measuring cup to pour the recommended amount (about 650-700ml) of SAE 10W-40 or your chosen transmission oil into the filler hole using your funnel.
    • Install the filler cap securely when done.
  5. Check Oil Level
    • On many CR250s, there's a oil check bolt: remove it and see if oil starts to flow out. If it does, the level is correct; if not, add oil slowly until you see it drip or flow out, then reinstall the check bolt.
    • For the 1978 model, if there's only a sight screw or level plug, use that to check oil; otherwise, be very careful to measure the quantity accurately.
  6. Inspect for Leaks & Disposal
    • Start the engine, let it idle for a couple of minutes, then inspect for leaks from the drain and fill bolts.
    • Properly dispose of your old oil in accordance with local regulations, never pour it down a drain or into the ground.

Specific 1978 Honda CR250 Call-Outs

  • Vintage hardware and gasket care:– Drain and filler threads may be softer or galled after years of service—avoid overtightening and always check washers.
  • Transmission-only oiling:– The 1978 CR250 is a two-stroke designed for transmission/clutch oil only. The engine itself is lubricated by the oil in the premix fuel (typically mixed at a 32:1 ratio). No engine sump oil needs changing for this bike; always maintain quality premix oil for the top end.
  • Inspect for common issues in old bikes:– Watch for shifter shaft seal leaks and possible gasket seepage, both common in vintage models. Consider replacing seals or gaskets during oil changes if you detect any drips.
  • Change frequency:– For best performance, change the transmission oil every 3 rides or at 7.5-hour intervals, whichever comes first, especially if riding aggressively or racing.

Troubleshooting & Pro Tips

  • Always use high-quality oil that meets current motorcycle gear oil specs.
  • If you overshoot your fill, gently tip the bike upright and remove the check bolt to let excess drain.
  • If your oil comes out with lots of metallic particles, plan for further maintenance to check for worn gears or clutch plates.

Need more classic bike advice? Reach out to MotoSport.com's service pros for expert advice and all the parts and products you need for your 1978 Honda CR250. Regular oil changes keep these legendary machines running hard for years to come.

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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.