How to Change the Oil in a 2008 GAS GAS EC 300: A MotoSport.com Exclusive Guide

Shop parts for a 2008 GAS GAS EC 300 Dirt Bike.

Changing the transmission oil in your 2008 GAS GAS EC 300 is essential maintenance for longevity & smooth performance. While the task is routine for most two-stroke dirt bikes, each model year and make can introduce unique quirks—this blog covers everything an EC 300 owner needs for a robust, clean oil change.

Tools and Materials Needed

  • 10mm or 12mm socket wrench or Allen/Hex key (for the drain plug and, if equipped, skid plate removal)
  • Oil catch pan
  • Fresh transmission oil (recommended: 10W-30 API SF or SG grade)
  • Measuring cup (for 900cc of oil)
  • Funnel (long and narrow for the recessed fill hole)
  • Clean rags
  • Replacement O-ring for drain plug if needed
  • Gloves (optional, but recommended)

Preparation and Critical Model-Specific Notes

  • Ensure the engine is cool to the touch before starting. If the bike was used, wait 10–20 minutes to avoid burns and allow the oil to settle.
  • Oil Capacity: The EC 300 transmission holds 900cc of oil.
  • Drain Plug & Fill Hole Details: The fill hole is small and deeply recessed, requiring patience and a good funnel for refilling. The drain plug uses a small O-ring prone to pinching, so inspect and replace it as needed to prevent leaks. Over-tightening can cause O-ring damage or strip the threads, so torque gently and evenly.
  • Access Issues: Skid plate removal is often necessary for easy access to the drain bolt, particularly on models with aftermarket or factory plate guards. Use an appropriately sized Allen key or socket to remove the skid plate and reinstall it after the change.

Step-by-Step Oil Change Instructions

  1. Position the Bike
    • Set the bike upright on a stable stand for level draining and filling.
  2. Remove the Skid Plate (if equipped)
    • Use the Allen or socket wrench to take off the skid plate, exposing the drain bolt underneath the engine. This step is crucial, as the plate may prevent access to the drain plug.
  3. Drain the Oil
    • Place your oil catch pan directly under the drain plug.
    • Use the correct socket or Allen to remove the drain plug. Allow all oil to drain – this may take several minutes.
    • Inspect the O-ring. Replace if pinched, flattened, or cracked. This small part is key to preventing future leaks.
  4. Reinstall the Drain Plug
    • Clean the plug and its threads. Install a fresh O-ring if needed.
    • Thread the plug in by hand to avoid cross-threading, then use your tool to gently snug it down. Do not over-tighten.
  5. Add New Oil
    • Locate the small, recessed fill plug (on the right or left side case cover, depending on sub-model and country). Remove with the appropriate socket or Allen key.
    • Using a measuring cup, pour 900cc of 10W-30 oil into a long, narrow funnel. Slowly add oil to the fill hole. Due to the small opening, pour in increments and allow oil to settle between pours to avoid overflow. Patience is essential for this step.
    • If oil begins to back up, stop and let it settle before adding more.
  6. Check Oil Level and Leaks
    • Some models have a sight glass or dipstick – if available, check the level. Otherwise, trust your measured volume.
    • Wipe down any excess oil, reinstall the fill plug, and torque gently.
    • Start the engine and let it idle for 1–2 minutes. Turn off and wait; inspect the drain and fill plug areas for leaks.
  7. Reattach Skid Plate
    • Reinstall the skid plate if it was removed. Tighten all fasteners securely but avoid over-torquing to prevent thread damage.
  8. Dispose of Used Oil Responsibly
    • Take the old oil to a recycling center or auto parts store that accepts used oil.

Special Tips for the 2008 GAS GAS EC 300

  • The fill hole is exceptionally small and can be frustrating—don't rush, as rapid filling may cause spillage or air pockets, resulting in underfilling or overflow.
  • The O-ring on the drain plug is delicate; always have a spare on hand. Tighten the drain plug just until snug to avoid leaks; over-tightening is a common mistake and can damage the case or the O-ring seal.
  • Oil grade and amount matter: Using the recommended oil and exact volume is critical for transmission performance and clutch longevity. The EC 300 uses 900cc (0.9L) of transmission oil—double-check your manual if in doubt.
  • If you notice metallic shavings or unusual residue in the drained oil, consider checking for premature wear or other issues.

Conclusion

The 2008 GAS GAS EC 300 isn't difficult to maintain, but its quirky small fill hole and sensitive drain plug O-ring demand extra care and patience. By following these detailed steps, you'll keep your transmission running smooth and your weekends on the trails trouble-free.

For more model-specific dirt bike maintenance tips, trust MotoSport.com—your home for parts, advice, and how-tos.

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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.