How to Change the Transmission Oil in a 1998 Suzuki RM250

Shop parts for a 1998 Suzuki RM250 Dirt Bike.

Regular transmission oil changes are critical for maintaining the performance and longevity of your 1998 Suzuki RM250. This two-stroke dirt bike requires proper lubrication of its transmission for smooth engine function and gear shifts. Below, you'll find a step-by-step guide specifically for this make and model, including tools needed, oil specifications, and unique call-outs every RM250 owner should know.

Tools and Supplies Needed

  • 8mm Allen wrench (for oil check bolt, if needed)
  • Socket wrench set
  • Oil drain pan
  • Funnel
  • Clean rags or shop towels
  • 750 ml of high-quality 10W-40 transmission oil (such as MOTUL 800 2T Factory Line Off Road or equivalent)
  • Gloves and eye protection (recommended)
  • Torque wrench (for precise reinstallation of drain plug)

Oil Specifications and Capacity

  • Oil type:– 10W-40, API SG/SH/SJ/SL with JASO MA/MA1/MA2, or MOTUL 800 2T Factory Line Off Road
  • Oil volume:– 750 ml (0.8 US qt)
  • Transmission only:– Do not use pre-mix oil intended for your fuel mix in the transmission–use transmission-specific oil as described above

Step-by-Step Oil Change Procedure

  1. Warm up the engine
    Briefly start and idle your RM250 for a few minutes to allow the transmission oil to become less viscous. This ensures a more thorough drain and flush of contaminants.
  2. Stabilize the motorcycle
    Secure the bike upright on a level surface or stand. Ensure it's as vertical as possible so the oil drains correctly.
  3. Locate the drain plug
    The transmission oil drain plug is situated under the engine case. Place your oil drain pan directly beneath this point.
  4. Remove the filler plug and drain plug
    – Remove the oil filler cap located on the right side of the engine to allow air in.
    – Use your socket wrench to remove the drain plug underneath and let the oil completely drain out.
    – Allow several minutes for all oil to exit.
  5. Inspect and clean
    Wipe the drain plug clean (check for metal shavings–some is normal, but a lot means possible internal wear).
  6. Reinstall the drain plug
    Reinstall and torque the drain plug to 21 N·m (15 lb-ft) to prevent stripping or overtightening.
  7. Add new oil
    Insert a funnel into the oil filler opening. Pour 750 ml of the specified 10W-40 transmission oil into the case.
  8. Check the oil level
    Suzuki RM250s have an oil check bolt hidden behind the wires near the chain guard. To access:
    • Remove the chain guard
    • Move wires aside to locate the Allen head check bolt
    Remove the check bolt briefly; oil should just seep out to indicate proper fill level.
    Re-tighten the check bolt to 5.5 N·m (4 lb-ft) when done.
  9. Refit the filler cap
    Tightly reinstall the filler cap. Wipe away any spilled oil.
  10. Run the engine and recheck
    Start the bike, idle for 30-60 seconds, then shut it down and recheck for leaks or oil level errors.

Important Model-Specific Notes for the 1998 Suzuki RM250

  • This is a two-stroke bike. Only the transmission requires oil changes–engine lubrication comes from the fuel pre-mix (30:1 ratio fuel oil mixture in tank).
  • Transmission oil is typically separate–never use pre-mix or two-stroke oil in the transmission compartment.
  • If you have difficulty finding the oil check bolt, know it is sometimes concealed behind wires and partially obscured by the chain guard–a unique quirk of the RM250 of this vintage.
  • Overfilling or underfilling can potentially cause clutch or transmission problems. Always check the oil level after every change.
  • Monitor for excess metal debris on the drain plug magnet as this could be an early sign of bearing or gear damage. A small “fuzz” is normal; large chunks or shavings are not.

Disposal Tips and Environmental Caution

  • Dispose of old oil responsibly at an approved recycling center.
  • Never pour used oil onto the ground or into drains, as it is harmful to the environment.

Regularly maintaining your RM250’s transmission oil—combined with proper fuel/oil pre-mix—ensures not only a longer life for your bike, but also optimal clutch and gear performance on every ride. For genuine parts, the right oil, and more Suzuki maintenance guides, trust MotoSport.com—the leader in off-road performance and know-how.

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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.