How to Change the Oil in a 1988 Suzuki RM250

Shop parts for a 1988 Suzuki RM250 Dirt Bike.

Changing the oil in your 1988 Suzuki RM250 is a key part of regular maintenance that keeps your bike running smoothly and prolongs engine life. Though the RM250 is a two-stroke dirt bike, it uses transmission oil rather than engine oil, as lubrication for the moving parts in the transmission case. Below you'll find a complete, proprietary MotoSport.com guide, including required tools, model-specific tips, and step-by-step instructions.

Tools & Supplies Needed

  • Socket wrench and sockets (for drain and fill plug – typically 12mm or 14mm, confirm size)
  • Allen wrench set (for oil check bolt access, usually 5mm or 6mm hex)
  • Torque wrench
  • Drain pan
  • Shop towels/rags
  • Funnel
  • Measuring cup
  • Replacement transmission oil:
    • Recommended type: SAE 10W-40 transmission oil (non-friction modified, JASO MA/MA1/MA2 compliant)
    • Recommended volume for oil change: 750ml (0.8 US qt)
  • New crush washer for the drain plug (if needed)

Special 1988 Suzuki RM250 Call-Outs

  • This model is a two-stroke: There is no engine oil; only the transmission uses oil. The engine itself gets lubrication from the pre-mixed fuel (gas/oil at 30:1 ratio, typically Motul 800 2T or equivalent).
  • Oil check bolt location is easily missed: It’s often hidden behind wires and the chain guard on the left side of the bike. Removing the chain guard may be necessary to access it.
    Tip: The oil check bolt uses an Allen key and is essential for verifying correct oil level after refilling.
  • Drain plug torque spec: 21 N·m (15.0 lb-ft) – do not overtighten.
  • Use a good quality 2-stroke transmission oil: Avoid friction-modified or synthetic oils not designed for two-stroke transmission use.

Step-by-Step Oil Change Instructions

  1. Warm up the engine:
    • Idle the bike for 2–3 minutes. This helps oil flow out more easily, carrying contaminants with it. Do not overheat or ride hard, just enough to get the gearbox warm.
  2. Stabilize the Bike:
    • Place the bike on a stand or level ground so it remains vertical during the service. Keep it upright for complete draining and accurate refill level.
  3. Locate and Remove the Filler Cap:
    • Remove the filler cap, typically on the left crankcase. This allows oil to drain faster by letting air in.
  4. Position the Drain Pan:
    • Place a drain pan directly under the crankcase oil drain plug, beneath the engine.
  5. Remove the Drain Plug:
    • Using the appropriate socket, unscrew and remove the drain plug. Allow oil to drain completely. Take care: the oil may be hot.
    • Inspect the crush washer and drain plug for wear or metal debris.
  6. Replace and Torque the Drain Plug:
    • Once oil has fully drained, wipe the area clean and screw the drain plug back in with a new crush washer if necessary.
    • Tighten to 21 N·m (15.0 lb-ft). Do not overtighten.
  7. Add New Transmission Oil:
    • Using a funnel, pour in 750ml (0.8 US qt) of SAE 10W-40 oil into the filler opening. Use a measuring cup for accuracy.
  8. Check Oil Level Via Check Bolt:
    • Locate the oil level check bolt (Allen screw), usually behind the chain guard and wires on the left side. Remove the bolt.
    • With the bike upright, oil should just begin to seep out of the check bolt hole—this means the level is correct. If not, add small amounts of oil until it drips from the hole, then reinstall the bolt (torque spec: 5.5 N·m or 4.0 lb-ft).
    • Reinstall chain guard and any wires if removed.
  9. Replace the Filler Cap:
    • Hand-tighten securely.
  10. Wipe and Clean Up:
    • Wipe away any oil drips with shop towels. Dispose of old oil responsibly at a recycling center.
  11. Test Ride and Recheck:
    • After a short ride or warm-up, shut down and check for leaks at the drain, check, and fill points. Top up oil if necessary.

Additional RM250 (1988) Oil Change Notes

  • The RM250 is designed for hard motocross riding; keep oil changes regular (every 3–5 rides, or after heavy use) to maintain shifting performance and clutch life.
  • Avoid using ATF or engine oil not specifically designed for 2-stroke transmissions, as this can harm clutch components.
  • Always double-check your owner’s/service manual for specs and oil recommendations, as changes in previous ownership or modifications may exist.

Proper oil maintenance is vital for your 1988 Suzuki RM250. Following these steps ensures smooth gear changes, clutch performance, and long-term durability so you keep riding strong.

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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.