How to Change the Oil in a 2018 Honda CRF450RX

Shop parts for a 2018 Honda CRF450RX Dirt Bike.

Regular oil changes are essential to keep your 2018 Honda CRF450RX running at peak performance. Honda recommends changing the oil and oil filter every 15 hours of riding or after every six races, though many riders prefer to change it even more frequently to ensure optimal engine protection. The process is straightforward and, with the right tools and supplies, can typically be completed in under 30 minutes.

Tools and Supplies Needed

  • 8mm and 10mm sockets for bolts and engine guards
  • Ratchet (socket wrench)
  • 10mm Allen wrench for certain drain bolts
  • Torque wrench (for precise reassembly)
  • Oil drain pan
  • Honda CRF450RX oil filter (OEM recommended)
  • Honda 20W-50 engine oil or HP4 synthetic oil (be sure to avoid oils with moly additives unless recommended)
  • New crush washer for drain bolt and new O-ring for filter cover
  • Rags or shop towels
  • Funnel (especially for small, hard-to-reach fill ports)
  • Measuring cup (for accurately refilling oil to specified level)
  • Rubber gloves (optional, for keeping hands clean)
  • Contact cleaner (optional for cleaning up oil residue)

Step-by-Step Instructions

  • Warm up the engine:

    Start your CRF450RX and let it run for about one minute. Warming the oil helps it flow out more completely, carrying more contaminants with it.

  • Remove the engine guard/skid plate:

    If fitted, use your 8mm or 10mm socket to remove the bolts securing the left side engine guard or the full skid plate, allowing easier access to the drain bolt and oil filter cover.

  • Remove the oil fill cap:

    Unscrew the oil fill cap so air can enter the system as the oil drains, allowing for a faster, more thorough drain.

  • Place the oil drain pan:

    Position a drain pan directly beneath the engine's oil drain bolt.

  • Remove the drain bolt:

    Using a 10mm socket or Allen wrench, loosen and remove the oil drain bolt at the lower rear of the crankcase. Take care not to burn yourself on hot oil. Replace the crush washer with a new one to prevent leaks upon reassembly.

  • Allow oil to drain completely:

    Let all the oil in the engine empty into the pan. A brief idle or tilt of the bike may help remove residual oil.

  • Remove the oil filter cover:

    Use an 8mm socket to remove the bolts holding the oil filter cover on the left side of the engine.

  • Replace oil filter:

    Pull out the old filter and O-ring. Clean the filter cavity with a rag, ensure the O-ring surface is clean, and fit a new O-ring and oil filter. Insert the new filter in the correct orientation as indicated in your manual.

  • Reinstall the oil filter cover:

    Fit the cover back, hand-tighten the bolts, then torque them to 9 foot-pounds (12 Nm) using your torque wrench.

  • Reinstall the engine guard/skid plate:

    Once service is complete, replace the engine guard or skid plate and tighten bolts securely.

  • Refill with fresh oil:

    Pour in the required amount of Honda 20W-50 oil (check your owner's manual for exact volume, usually just under a quart for the 2018 CRF450RX). A funnel will help avoid spills, especially as the fill port is small. Ensure the bike is upright and level for an accurate fill.

  • Check the oil level:

    After filling, check the oil level through the sight glass or–on older models–using the dipstick. Top off as necessary. Replace the oil filler cap securely.

Important 2018 CRF450RX-Specific Notes

  • Be aware of the small fill port size:

    The fill port is slightly small, so a narrow funnel works best to avoid spills. Some owners also add oil through the crankshaft position sensor port (after wiping clean), which is considered quicker by some mechanics, though you should follow Honda‘s official recommendations.

  • Oil type selection:

    Honda recommends its own oil, but you may use an equivalent high-quality 20W-50 or HP4 synthetic oil. If you ride hard on the clutch, avoid synthetic blends with moly additives unless approved by Honda.

  • Torque specifications:

    Always use a torque wrench, particularly for the filter cover (9 foot-pounds – 12 Nm) and drain bolt (as specified in your service manual).

  • Replace all gaskets and O-rings:

    To maintain proper sealing and prevent leaks, always use new copper crush washers and filter cover O-rings at every oil change.

  • Dispose of old oil responsibly:

    Take used oil and filters to a proper recycling facility.

Quick Reference: Oil Change Interval

  • Every 15 hours of engine run time or after every 6 races

Summary

Routine oil changes for your 2018 Honda CRF450RX take only a few tools and parts and can easily be performed at home. Remember to use the correct oil, replace all necessary gaskets and filters, and torque everything to the proper specification for best results. For more tips, parts, and everything dirt bike, visit MotoSport.com.

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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.