How to Change the Oil in a 1978 Honda XR350

Shop parts for a 1978 Honda XR350 Dirt Bike.

Keeping your vintage 1978 Honda XR350 in peak running condition means staying on top of regular oil changes. This guide has been crafted exclusively for MotoSport.com to help owners of the XR350 get the most out of their classic dirt bike. Below you'll find all the tools required, detailed steps, and important model-specific considerations to ensure your next oil change is hassle-free and keeps your XR350 running strong.

Tools & Materials Needed

  • Socket wrench set (including 8mm socket for drain plugs)
  • Oil drain pan
  • New engine oil (Consult your manual; typically 10W-40 for air-cooled Hondas)
  • Replacement oil filter
  • Replacement oil filter O-rings (recommended)
  • Funnel
  • Shop rags
  • Torque wrench (recommended)
  • New crush washer for drain bolt (if needed)
  • Gloves and eye protection

Steps to Change the Oil

  1. Warm Up the Engine
    • Start the XR350 and let it idle for a few minutes. This helps the oil warm up and thin out, ensuring it drains completely.
  2. Turn Off and Secure the Motorcycle
    • Shut off the engine and place the bike on a level surface, using a center stand or sturdy support.
  3. Remove Skid Plate (if equipped)
    • Some XR350 models have a skid plate that may need to be removed to access the drain plugs.
  4. Locate and Remove the Drain Plugs
    • The XR350 uses a dry sump system. Oil is stored in the frame tubes, and two drain points are used:
    • Engine drain plug: Bottom of the engine cases.
    • Frame drain plug: Bottom of the front frame downtube. This is an aluminum plug that doubles as a mount for the skid plate. Do not over-tighten to avoid cracking or twisting off the plug—replacement parts for this vintage bike are scarce, so extra care is critical.
    • Place the drain pan underneath, then use the socket wrench to carefully remove both drain bolts, allowing all oil to drain out.
    • If a crush washer is present and appears damaged, replace it before reinstallation.
  5. Replace the Drain Plugs
    • Once oil has fully drained, reinstall both drain plugs. Tighten by hand first, then use the torque wrench to finish–I recommend staying snug, as the aluminum frame plug is delicate.
  6. Remove and Replace the Oil Filter
    • Locate the oil filter cover (typically found on the right engine case).
    • Remove the cover bolts, gently remove the cover and extract the old filter.
    • Inspect the oil filter O-rings; ideally, replace with new O-rings. If unavailable but the old ones are undamaged, reuse carefully.
    • Wipe the filter seat area clean, install the new filter (correct orientation), put the cover and bolts back, and tighten evenly.
  7. Add Fresh Oil
    • Remove the oil fill cap on the right side of the engine.
    • Using a funnel, pour in the recommended amount of oil (typically between 1.7 and 2 quarts; confirm with your service manual for the specific year XR350).
    • Replace and secure the oil fill cap.
  8. Check Oil Level (Critical for XR350 Dry Sump System)
    • Start the engine and let it run for 2-3 minutes to circulate the new oil.
    • Shut it off, wait around 30 seconds, and then check oil level using the dipstick or oil window. Do not check oil level cold or directly after pouring–it must circulate first.
    • Add oil if necessary until it falls between the upper and lower marks. More oil is better than less for these air-cooled engines for enhanced heat dissipation.
  9. Final Steps
    • Wipe down any spills or drips.
    • Check for leaks at the drain plugs and filter area.
    • Safely dispose of used oil and filter per local regulations.

Model-Specific Call-Outs for the 1978 Honda XR350

  • Dry Sump Oil System: For the XR350, oil is stored in the frame, not the crankcase. Always drain and refill both the engine and frame. Failure to do so can lead to improper oiling and serious engine damage.
  • Aluminum Frame Drain Plug: The frame drain plug is delicate. Do not overtighten—use a torque wrench if possible. If stripped or cracked, replacement parts are hard to source.
  • Oil Level Checking: The correct procedure is to run the engine, let it sit for about 30 seconds, then check–never check the dipstick cold. This ensures an accurate reading as oil circulates between frame and engine.
  • Filter O-Rings: It's best to replace the O-rings each oil change. If you don't have new ones and the old set is in good condition, you can reuse, but inspect for flattening or cracking.
  • Engine Oil Capacity: Most air-cooled single-cylinder Hondas from this era take between 1.7 and 2 quarts after a filter change, but always verify your specific model's needs.

Quick Tips

  • Consider synthetic oil for better engine longevity, especially under hot conditions.
  • Regular oil changes prolong engine life – older air-cooled engines benefit from fresh oil more often than modern bikes.
  • If you lose or damage the frame drain plug, sourcing a replacement can be difficult; treat it with care.

This exclusive MotoSport.com guide provides everything you need for a safe, effective oil change on your classic 1978 Honda XR350. Keep these vintage machines running for generations with diligent maintenance and regular oil changes.

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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.