How to Change the Oil in a 2018 Honda CRF150R Big Wheel

Shop parts for a 2018 Honda CRF150R Big Wheel Dirt Bike.

Keeping the oil fresh in your 2018 Honda CRF150R Big Wheel is crucial for top performance and long engine life. This dirt bike features a separate oil design: one side for the engine and one for the transmission/clutch. Below is a detailed and proprietary step-by-step guide—exclusive to MotoSport.com—covering tools, steps, and specific call-outs unique to the CRF150R Big Wheel.

Tools and Supplies Needed

  • 8mm, 10mm, and 12mm sockets and ratchet
  • Oil drain pan
  • Funnel
  • New engine oil (Honda GN4 10W-40 recommended)
  • New transmission oil (Honda GN4 10W-40 recommended)
  • Replacement oil filter (OEM or HIFLO HF116 recommended)
  • New O-ring for oil filter cover (recommended, not always mandatory)
  • New crush washers for both drain bolts
  • Clean shop towels or rags
  • Service manual or owner’s manual (for torque specs, if needed)
  • Gloves and eye protection

Oil Capacity Specifications

  • Engine oil (with filter change): 590cc
  • Engine oil (without filter change): 560cc
  • Transmission oil: 580cc

Important Model-Specific Notes

  • The 2018 CRF150R Big Wheel has separate compartments for engine oil (right side) and transmission/clutch oil (left side). Both must be changed for a full service. Never mix up the fill locations.
  • Honda GN4 10W-40 is the manufacturer’s go-to oil for both sides, but any high-quality JASO MA-rated 4-stroke motorcycle oil is acceptable.
  • Always use new crush washers on the drain bolts to prevent leaks.
  • Be very careful not to over-tighten the drain bolts. The case threads are relatively soft and can strip easily.

Step-by-Step Process

  1. Warm the Engine
    Run your CRF150R for a few minutes to warm up the oil, which helps it drain completely. Never perform this on a hot engine; allow it to cool just enough to touch safely.
  2. Prepare Your Work Area
    Place the bike upright on a stand. Ensure all your tools and supplies are within reach, and put the drain pan directly under the engine.
  3. Remove the Skid Plate (if equipped)
    Some models may have a skid plate–remove this if access to drain bolts is hindered.
  4. Drain the Engine Oil
    Locate the engine side drain bolt (right side, bottom of engine). Using your 12mm socket, carefully remove the bolt and crush washer. Allow the oil to drain fully.
    Tip: Remove the fill cap on the right side while oil drains to vent the system and speed drainage.
    Replace the crush washer and reinstall the drain bolt snugly, torquing to Honda specs if available.
  5. Drain the Transmission/Clutch Oil
    Repeat the process on the left side: remove the drain bolt and crush washer for the transmission (left bottom of engine).
    Let all oil drain. Replace with a new crush washer and reinstall the bolt. Torque to spec.
  6. Replace the Engine Oil Filter
    Locate the oil filter cover on the right side of the engine (three bolts). Remove them using an 8mm socket, carefully lift the cover, and remove the oil filter.
    Inspect the O-ring on the cover; replace if damaged.
    Install the new oil filter with the correct orientation (usually the rubber seal faces out).
    Reinstall the cover, making sure the O-ring is properly seated. Torque bolts evenly and carefully.
  7. Add Fresh Oil
    • Engine side (right): Add 590cc of new oil if replacing the filter, or 560cc if not.
    • Transmission side (left): Add 580cc of new oil.
    Use a funnel to avoid spills. Replace the fill caps after adding oil.
  8. Initial Check and Test Run
    Start your bike and let it idle for a minute, checking underneath for leaks. Shut it off and let it sit for two minutes.
  9. Final Level Check
    Using the dipstick (engine side) or inspection bolt (transmission side), re-check the oil levels. Add more oil if necessary to reach the correct mark.
    Note: Oil expands when hot; check levels with the bike upright and level, not resting on its side stand.
  10. Clean Up and Reset Maintenance Timer
    Record the oil change in your logbook. Reinstall the skid plate if removed, clean any spills, and dispose of used oil properly.

Frequency and Filter Advice

  • Engine oil: Change every 6 hours of riding (or after each race/practice session).
    Oil filter: Change every second oil change, or about every 12 hours, using OEM or reputable aftermarket (such as HIFLO HF116 filters recommended for value and quality).
  • Transmission oil: Change every 12 hours, or sooner for racing/harsh conditions.

Special Tips and Warnings

  • Only use the correct oil type and quantity for each side. Overfilling or underfilling can cause serious engine damage.
  • Do not over-tighten the drain and cover bolts—stripped cases are an expensive fix.
  • Always double-check both compartments are filled before you run the engine to prevent catastrophic failure.
  • If racing/extreme riding, consider changing engine and transmission oil more frequently than the manual suggests.

Congratulations. You’ve successfully changed the oil and filter on your 2018 Honda CRF150R Big Wheel—ensuring maximum reliability and performance on or off the track. For more dirt bike maintenance guides and essential parts, MotoSport.com has you covered.

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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.