How to Change the Oil in a 2008 Honda CRF150R Big Wheel

Shop parts for a 2008 Honda CRF150R Big Wheel Dirt Bike.

Changing the oil in your 2008 Honda CRF150R Big Wheel is a fundamental maintenance task that ensures a long and healthy engine life. This bike is unique because it has two separate oil compartments: one for the engine and one for the transmission/clutch side. Below, you'll find a complete, proprietary MotoSport.com guide for changing the oil in both compartments.

Tools and Supplies Needed

  • Socket wrench set (8mm and 17mm sockets recommended)
  • Drain pan
  • Oil filter (Honda part or equivalent)
  • New oil - Honda GN4 10W-40, or a high-quality 10W-40 motorcycle oil (approx. 590cc for engine side; 580cc for clutch/trans side; see notes below)
  • Transmission oil (optional: 80W or 85W gear oil if you use specific transmission oil on the clutch side)
  • New drain plug crush washers
  • Clean rags
  • Funnel
  • Torque wrench
  • O-ring for oil filter cover (if needed)
  • Gloves (for clean hands and heat protection)

Step-by-Step Instructions

  1. Warm up the engine:
    • Start the bike and let it idle for 2-3 minutes. This warms and thins the oil for better draining.
  2. Turn off the engine & secure the bike:
    • Place the bike on a stand or secure surface, engine off, transmission in neutral.
  3. Remove skid plate (if equipped):
    • Use your socket set; some models may have a protective plate covering drain bolts.
  4. Locate drain bolts:
    • Engine side drain bolt: Usually 17mm, located on the bottom of the right side of the engine case.
    • Transmission (clutch) side drain bolt: Often 8mm or 12mm; check the left/bottom side of the case. There are two separate drain bolts for the two oil compartments.
  5. Drain the oil:
    • Position the drain pan under the first drain bolt (engine side), loosen and remove carefully.
    • Allow the oil to drain completely; replace the crush washer on the drain bolt.
    • Repeat on the transmission side with the second drain bolt.
  6. Remove and replace the oil filter:
    • Remove the oil filter cover (right side, three bolts).
    • Take out the old oil filter and replace with a new one. Lightly oil the new O-ring and ensure it's seated.
    • Reinstall the oil filter cover and torque to spec.
  7. Reinstall drain bolts:
    • With new crush washers in place, hand-thread then torque each bolt to manufacturer specifications to avoid stripping.
  8. Refill with new oil:
    • Engine side: Add 590cc (milliliters) of oil (or 560cc if just changing the oil and not the filter).
    • Clutch side: Add 580cc of oil.
    • Note: You can use the same 10W-40 oil on both sides, or motorcycle-specific transmission oil (80W or 85W) on the clutch side if desired.
    • Use a funnel for clean pouring.
  9. Double-check oil levels:
    • Wipe dipsticks clean, thread and check level to ensure it's correct. Don't overfill.
  10. Run and re-check:
    • Start the engine and let it idle for 2-3 minutes.
    • Shut off and wait a few moments.
    • Check both oil levels again and top off if needed.
  11. Final checks:
    • Inspect for leaks around drain plugs and oil filter cover.
    • If your bike has a skid plate, reinstall it.
    • Clean any spilled oil.

Special Call-Outs for 2008 Honda CRF150R Big Wheel

  • Unlike many dirt bikes, the CRF150R Big Wheel uses separate oils for engine and clutch/tranny sides—never mix or cross-fill.
  • Do not overtighten or strip the drain plug bolts;– these are easily damaged. Use new crush washers with every change.
  • Check your owner's manual for proper oil types and capacities; always use recommended oil grades.
  • If you're racing or riding hard, consider changing oil more frequently than the manual suggests.
  • Allow the O-rings for the filter cover to be replaced as needed to avoid leaks.

Questions and Expert Tips

  • If unsure about torque specs, consult your owner's manual or a reputable service manual.
  • When replacing the filter, visually inspect the old oil and filter for signs of metal shavings or contamination.
  • Disposal: Always dispose of used oil and filters properly—never dump outdoors.

This exclusive guide from MotoSport.com ensures your 2008 Honda CRF150R Big Wheel will stay in top shape, maximize performance, and minimize engine wear. Happy 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.