How to Change the Oil in a 1999 Kawasaki KLX300

Shop parts for a 1999 Kawasaki KLX300 Dirt Bike.

Changing the oil in your 1999 Kawasaki KLX300 is a crucial maintenance step to prolong the life and performance of your dirt bike. This proprietary MotoSport.com guide will walk you through everything you need to complete the job confidently, with specific tips for this model year.

Tools and Materials Needed

  • 14mm socket and ratchet (for drain plug)
  • 8mm socket or 11/16" (for oil filter cover)
  • Measuring cup (optional)
  • Funnel (optional but helpful)
  • Drain pan
  • Shop rags or paper towels
  • New oil filter (e.g., High Flow HF12 or OEM equivalent)
  • Fresh 10w40 full synthetic motorcycle oil (you’ll need 1.2 – 1.5 liters)
  • Nitrile gloves (recommended)
  • Small dab of grease or Vaseline (for filter spring)

Model-Specific Call-Outs for the 1999 KLX300

  • This bike’s drain plug is located toward the back of the skid plate on the left side.
  • Oil sight glass is behind the brake lever—use this to check your fill level.
  • Do not overtighten the drain plug—threading is easy to damage on KLX engines.
  • Capacity is approximately 1.2 liters but check your manual and the sight glass for exact fill.

Step-by-Step Oil Change Instructions

  1. Prep Your Work Area
    • Work in a well-ventilated space and plan for a bit of a mess—used oil can splash.
    • Start with the engine warm (run bike for a few minutes); this helps oil drain completely.
  2. Remove the Oil Fill Cap
    • It’s on the right side of the engine. Removing the cap now helps the oil drain smoothly later.
  3. Locate and Remove the Drain Plug
    • The drain plug is underneath, just left of center by the skid plate. Use a 14mm socket. Place your drain pan below.
    • Carefully loosen and remove the plug. Let the oil drain fully (this might take a few minutes).
  4. Remove the Oil Filter Cover
    • Use an 8mm socket or 11/16". The cover is also on the right side of the engine.
    • Once the cover is off, take out the old filter. Pay attention to the orientation of the filter and spring.
    • Clean the filter cavity using rags, removing any old oil and debris.
  5. Prepare and Install the New Oil Filter
    • Dab a little grease or Vaseline on the filter spring. This keeps it in place as you install the new filter.
    • Insert the new filter—make sure it’s seated the same way as the one you removed.
    • Reinstall and snug down the filter cover using the 8mm socket—don’t overtighten.
  6. Reinstall the Drain Plug
    • Replace the drain plug with the 14mm socket. Be firm, not aggressive: overtightening can strip the threads and lead to costly repairs.
  7. Add New Oil
    • Use a funnel to pour in 1.2 to 1.5 liters of 10w40 synthetic motorcycle oil through the fill cap opening.
    • Start with the lower amount, then check the sight glass. Add oil slowly until the level is centered in the glass while the bike is upright (not on the side stand).
  8. Let the Engine Idle, Then Double-Check Level
    • Start the engine and let it run for a minute to circulate the oil, then turn it off and wait a minute for oil to settle.
    • Check the sight glass and top off if necessary. Always maintain level in the center of the sight glass.
  9. Dispose of Old Oil Properly
    • Take used oil and the old filter to a proper recycling facility—never dump it in gutters or trash.
  10. Inspect for Leaks and Take a Short Test Ride
    • Look for any fresh oil drips around the drain plug or filter.
    • Take a short ride, then recheck the sight glass.

Bonus Tips for the 1999 KLX300

  • Always warm the engine before draining; it helps old oil flow out, carrying contaminants with it.
  • Have extra rags handy—KLX engines can make a mess during the drain step.
  • When using the sight glass, keep the bike upright (not on the kickstand) for an accurate reading.
  • Never exceed recommended tightening torque, especially on the drain plug. If you have a torque wrench, refer to your owner’s manual for specs.
  • Check your oil level after every couple of rides—KLX300s can burn or lose oil if ridden hard.

Conclusion

Changing the oil on your 1999 Kawasaki KLX300 isn’t just basic maintenance—it’s the secret to big mileage and peak power. With the proper tools, a methodical approach, and a few KLX-specific precautions, you’ll keep your bike tearing up the trails 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.