How to Change the Oil in a 1979 Suzuki RM250

Shop parts for a 1979 Suzuki RM250 Dirt Bike.

Changing the oil in your 1979 Suzuki RM250 is an essential maintenance step to keep your dirt bike running at peak performance. This process ensures the transmission is properly lubricated, reduces wear, and increases longevity. Below you'll find a comprehensive, step-by-step guide brought to you exclusively by MotoSport.com. We'll cover all the tools you need, detailed instructions, and important call-outs unique to your RM250.

Tools and Supplies Needed

  • 10mm and 12mm socket or wrench
  • Allen wrench set (for oil check bolt)
  • Drain pan
  • Funnel
  • Measuring cup or graduated oil jug
  • Clean shop rags/paper towels
  • Replacement crush washer (recommended)
  • Fresh transmission oil (SAE 10W-40 motorcycle gear oil, non-friction modified, approx. 750ml/0.8 US qt for a change)
  • Torque wrench
  • Nitrile gloves (optional, but recommended)

Step-By-Step Oil Change Procedure

  • Warm up the engine.
    Start your bike and let it idle for a few minutes. This heats the oil, allowing it to flow better and evacuate contaminants.
  • Stabilize the bike.
    Place the motorcycle upright on level ground. A bike stand or center stand works best.
  • Locate the drain plug and filler cap.
    The oil drain plug is on the underside of the crankcase. The filler cap is typically on the right engine case. Refer to your owner's manual to confirm location.
  • Remove the oil fill cap.
    This allows air to enter and helps the oil drain out fully.
  • Position your drain pan.
    Align it directly under the drain plug to avoid any spills.
  • Remove the drain plug.
    Use a 12mm socket or wrench. Carefully loosen and remove the drain plug, allowing the old oil to drain completely into your pan.
  • Inspect and replace the crush washer (if equipped).
    Crush washers reduce the risk of leaking; replace with a new one if worn or damaged.
  • Reinstall and torque the drain plug.
    Hand-thread the drain plug first to avoid cross-threading, then tighten it to 21 N·m (15.0 lb-ft) with a torque wrench for a proper seal .
  • Refill with fresh oil.
    Insert a funnel into the oil filler hole and pour in 750 ml (0.8 US qt) of SAE 10W-40 motorcycle transmission oil .
  • Check the oil level.
    Clean the area around the oil check bolt, which is located behind the chain guard near some wiring (unique to ‘79 RM250s). Use an Allen wrench to remove the check bolt. Oil should just reach the level of the bolt hole. Top-off or adjust as necessary .
  • Reinstall the oil check bolt and oil fill cap.
    Tighten both securely.
  • Start the engine and check for leaks.
    Let it idle for several minutes, shut it off, and inspect around the drain plug and filler for any leaks.

Important RM250 Model-Specific Callouts

  • Oil Check Bolt Location:
    Many owners miss this: on the ‘79 RM250, the oil check bolt is hidden behind the chain guard and some wires. To access, remove or move the guard and wiring—they often cover the access point. Use a moderate-length Allen wrench for best reach .
  • Oil Specification:
    Always use 10W-40 motorcycle gear oil—not engine oil. 2-stroke engines like the RM250 use oil in the transmission, not in the crankcase.
  • Check Washer/Gasket Condition:
    Early RM models are notorious for leaks if the drain plug washer isn't replaced during oil changes.

Tips for First-Time Oil Changers

  • Be patient during draining. Tilting the bike gently side-to-side may help remove all the old oil.
  • Always dispose of old oil safely and legally at a recycling center or auto parts store.
  • If you ride in wet or extreme conditions, change the oil more often than the manual recommends.

Routine oil changes are a vital part of maintaining your 1979 Suzuki RM250. Performing this basic service yourself saves money and allows you to bond with your machine. For genuine Suzuki parts, oil, and more tips, trust MotoSport.com—your dirt bike experts.

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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.