How to Change the Oil in a 1990 Suzuki DR350S

Shop parts for a 1990 Suzuki DR350S Dirt Bike.

Changing the oil in your 1990 Suzuki DR350S is essential for maintaining engine performance and longevity. This guide is exclusive to MotoSport.com and provides a thorough, step-by-step process, with model-specific callouts to ensure you get the job done right.

Tools and Supplies Needed

  • Socket Wrench Set (10mm, 12mm, 14mm, 17mm, 19mm sockets)
  • Flathead Screwdriver
  • Oil Catch Pan
  • Needle-Nose Pliers (helpful for removing screen filters)
  • Clean Rags
  • New Oil Filter (recommended: High Flow brand or equivalent)
  • 2 Quarts 10W40 Motorcycle Oil (check your manual for your climate)
  • Replacement Crush Washers and O-Rings for the drain bolt and filter cover
  • Gloves (for cleanliness and protection)

Special Notes for 1990 Suzuki DR350S Owners

  • This bike features a dry sump oil system – oil is stored in both the frame and engine sump.
  • Oil change involves draining oil from both locations and cleaning the frame’s internal filter screen if necessary.
  • The oil screen in the frame generally does not need cleaning every oil change, but check if you’re unsure when it was last serviced.

Preparation Steps

  • Warm up the engine: Run the engine for several minutes. Warm oil flows and drains better, bringing contaminants with it.
  • Stabilize the bike: Use a center stand or ensure it’s securely upright on level ground.

Step-by-Step Oil Change Process

  1. Remove the Skid Plate (if accessing oil screen):
    • Remove the four 12mm bolts. (If only draining oil and not cleaning the screen, you may skip this step.)
    • Set the skid plate and bolts aside.
  2. Drain the Engine Oil:
    • Place an oil catch pan under the crankcase drain bolt.
    • Remove the 14mm drain bolt from the engine’s bottom with your socket wrench.
    • Allow oil to fully drain. Replace the crush washer if worn.
  3. Drain the Frame Oil (Dry Sump Reservoir):
    • Locate the 12mm bolt on the oil reservoir (frame down tube near the engine).
    • Remove to drain the frame oil into your pan.
  4. (Optional) Clean the Frame Oil Screen:
    • If performing a thorough service, use needle-nose pliers to extract the mesh screen via the frame’s oil tube after removing the relevant bolt.
    • Inspect for debris. Clean the screen with solvent and replace any damaged O-rings; reinstall the screen.
    • Be cautious with old O-rings, as they are prone to damage during removal.
  5. Replace the Oil Filter:
    • Locate and remove the oil filter cover using your 8mm socket.
    • Take out the old filter—note orientation for the new filter.
    • Install the new filter. Do not forget to replace the cover O-ring and check for the small inner O-ring.
    • Reinstall the oil filter cover and bolts snugly, being careful not to overtighten.
  6. Reinstall the Drain Bolts:
    • Reinstall the engine and frame drain bolts with new crush washers to prevent leaks.
    • Tighten snugly but avoid overtightening to prevent stripping.
  7. Add Fresh Oil:
    • Add 2 quarts (or as specified in your manual) of 10W40 motorcycle oil through the filler cap on the engine or frame.
    • After adding 1.5 quarts, wait a minute, then finish adding until full.
  8. Prime and Circulate Oil:
    • With the spark plug disconnected or kill switch on, slowly kick the engine over several times to distribute oil before starting.
    • Reconnect, start the engine, and let it idle for a few minutes. Check for leaks.
  9. Check Oil Level:
    • Turn off the bike and wait about a minute for the oil to settle.
    • Check the level with the dipstick. Top off if needed (do not overfill).
  10. Replace the Skid Plate:
    • Once satisfied with the oil level and no leaks, reinstall the skid plate using the 12mm bolts.
  11. Dispose of Old Oil Responsibly:
    • Take used oil and filter to a recycling center.

Model-Specific Callouts and Tips

  • 1990 DR350S engines are dry-sump, with oil stored partly in the frame—always drain both locations for a complete change.
  • The inner filter cover O-ring and filter O-ring are critical to replace if worn to prevent oil leaks or pressure loss.
  • If you skip cleaning the frame’s oil screen, you can change oil without removing the skid plate for faster routine changes.
  • Always use oil formulated for motorcycles with wet clutches. 10W40 is recommended for most climates.
  • After refilling and running the bike, check for leaks not only at drain bolts but also around the oil filter cover.

Conclusion

With quality oil, new filters, fresh O-rings, and careful attention to DR350S's dual-drain design, you’ll keep your 1990 Suzuki running strong mile after mile. For all your Suzuki DR350S parts and oil change needs, trust MotoSport.com for genuine and reliable products.

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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.