How to Change the Oil in a 1999 Suzuki RM250

Shop parts for a 1999 Suzuki RM250 Dirt Bike.

Regular oil changes are vital for the performance and longevity of your 1999 Suzuki RM250. This model is a two-stroke dirt bike; therefore, oil changes refer to the transmission oil, as engine lubrication is mixed with fuel. Below, you’ll find a step-by-step proprietary guide from MotoSport.com—designed specifically for the 1999 RM250.

Tools and Supplies Needed

  • 10mm or 12mm socket or wrench (for drain plug and check bolt)
  • Allen key/hex wrench (for oil check bolt behind chain guard)
  • Drain pan
  • Measuring cup (such as a Ratio Rite or similar)
  • Funnel
  • Clean rag
  • Approved transmission oil (Typically SAE 10W-40 or a suitable 80W transmission oil like Maxima MTL)
  • Torque wrench (optional, for drain/filler bolts)
  • Gloves and safety glasses

Preparation

  • Warm up the motorcycle for a few minutes. This thins the oil and ensures a more complete drain.
  • Turn off the engine and let the bike cool for several minutes until parts are warm but not hot to the touch.
  • Stand the bike upright on level ground. Using a stand is recommended for stability.

Step-by-Step Instructions

  1. Locate the Drain Plug
    • The drain plug is under the engine near the bottom of the transmission case.
  2. Place the Drain Pan
    • Position the drain pan directly beneath the drain plug to catch all the old oil.
  3. Remove the Oil Filler Cap
    • The oil filler cap is located on the side of the crankcase. Unscrew and set it aside. This step prevents a vacuum and allows oil to drain faster.
  4. Remove the Drain Plug
    • Using the correct socket or wrench, carefully loosen and remove the drain plug. Allow the oil to drain completely–this may take a few minutes.
    • Inspect the drain plug for metal shavings or debris. Clean the plug and its sealing washer.
  5. Check for Remaining Oil
    • Tilt the bike gently side to side (while safely secured) to ensure all oil is drained.
  6. Reinstall the Drain Plug
    • Reinstall the drain plug and tighten securely. If possible, use a torque wrench set to manufacturer specs for the RM250.
  7. Measure and Add New Transmission Oil
    • Pour the recommended amount of transmission oil (typically 750ml–800ml for a 1999 RM250–always consult your manual for exact capacity).
    • Use a funnel for a clean pour.
  8. Check for Leaks
    • Wipe down any spilled oil and inspect for leaks around the drain plug and oil filler cap.
  9. Locate and Check the Oil Level
    • The RM250 features an oil level check bolt located behind the chain guard; you may need to move wires and use an Allen key to access it. Remove the check bolt–if oil seeps out, the level is correct. If not, add a small amount of oil, repeat the process until it seeps out, then reinstall and tighten the bolt.
  10. Final Steps
    • Reinstall the oil filler cap securely.
    • Wipe up any excess oil.
    • Dispose of used oil responsibly at a recycling center.

Important 1999 Suzuki RM250-Specific Call-Outs

  • The oil check bolt is difficult to spot–it's behind the chain guard, hidden by wires. You must remove the guard and move the wires to access it. Use a correct size Allen key (approximately 5mm). Don’t skip this to avoid running low or overfilling the transmission.
  • Only use SAE 10W-40 transmission oil or high-quality 80W transmission-specific fluids. Avoid using standard four-stroke engine oils, as the RM250 is a two-stroke and requires oil designed for gearboxes.
  • Do not overfill. Overfilling can increase transmission drag and may cause leaks or gearbox issues.
  • Recommended oil change interval: After every 5–10 hours of riding (more often in extreme or racing conditions).
  • Always check your manual for exact oil capacities and torque values for bolts.
  • Monitor your oil for color and debris; dark or gritty oil means it’s time for a change, or there could be a sign of internal wear.

Common Mistakes to Avoid

  • Using the wrong oil type or viscosity can damage the transmission.
  • Forgetting to reinstall or over-torquing the drain plug, which may strip threads.
  • Not checking the oil level via the specific check bolt behind the chain guard. This is unique to the RM250 and often missed.
  • Failing to replace sealing washers if needed, which may cause leaks.
  • Not disposing of old oil responsibly–never pour down drains or onto the ground.

Conclusion

Changing your 1999 Suzuki RM250’s transmission oil is a straightforward job, but attention to detail is crucial–especially given the unique position of the oil check bolt. Use quality transmission oil as per the manual and always double-check your oil level to keep your RM250 running strong, whether you’re out racing or enjoying the trails.

For premium OEM parts, race oils, or tools, trust MotoSport.com as your go-to source for everything Suzuki.

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Shop Oil Fillers and Drain Plugs for a 1999 Suzuki RM250 Dirt Bike.

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.