How to Change the Oil in a 2021 GAS GAS EX 350F

Shop parts for a 2021 GAS GAS EX 350F Dirt Bike.

Regular oil changes are vital to keep your 2021 GAS GAS EX 350F running at peak performance and to extend the lifespan of its engine. Follow this dedicated MotoSport.com guide, crafted specifically for your bike’s year, make, and model.

Tools and Supplies Needed

  • 10mm socket or wrench (drain plug)
  • 13mm socket or wrench (oil strainer bolt)
  • Needle nose pliers (oil strainer removal)
  • Torque wrench (to ensure proper reinstallation torque)
  • Drain pan
  • Rags or shop towels
  • Funnel (optional, for easy pouring)
  • Replacement oil filter (OEM recommended)
  • Crush washer for drain bolt
  • 1.0 liter Motorex Cross Power 4T 10W/50 full synthetic oil
  • Gloves (to keep hands clean)
  • Brake/contact cleaner (for cleanup, optional)
  • Grease (to lube the drain plug washer)

Steps to Change the Oil

  1. Warm Up the Bike
    • Start and idle the bike for about 2–3 minutes. Warm oil drains more completely and takes contaminants with it.
  2. Position Your Bike and Prep the Tools
    • Place the bike upright on a stand. Make sure your tools, drain pan, and new oil are within reach.
  3. Remove the Skid Plate (if equipped)
    • If your EX 350F has an aftermarket or OEM skid plate, remove it for clear access to the drain bolts and oil strainer.
  4. Drain the Engine Oil
    • Locate the main oil drain bolt under the engine (typically 10mm on the GAS GAS EX 350F models).
    • With the drain pan in place, carefully loosen and remove the drain bolt. Be mindful of hot oil.
    • Remove and replace the crush washer with a new one from your kit to prevent future leaks.
    • Allow oil to fully drain—this can take several minutes.
  5. Remove the Oil Strainer and Oil Filter
    • Find and remove the oil strainer bolt (13mm, left side of the engine casing).
    • After unscrewing the bolt, lightly use needle nose pliers to extract the oil strainer.
    • Clean the strainer with brake cleaner or compressed air if not replacing, then reinstall or set aside for now.
    • Locate the oil filter cover bolts and remove the cover. Take out the old oil filter and let any residual oil drain.
    • Clean the filter cavity and install the new OEM replacement oil filter included in your kit. Ensure the filter is properly seated—direction matters, so check your owner’s manual or match the orientation of the removed filter.
  6. Reinstall Drain Bolt and Strainer Bolt
    • Before reinstalling, lightly apply grease to the new crush washer. Hand-tighten the drain bolt, then torque to factory specs (consult your owner’s manual).
    • Clean and reinstall the oil strainer and its bolt with care, again torquing to specifications.
  7. Add New Oil
    • Open the oil fill cap on the right side of the engine.
    • Using a funnel, pour in 1.0 liter of Motorex Cross Power 4T 10W/50 full synthetic oil—this is the recommended quantity and viscosity for your 2021 EX 350F.
    • Replace the oil fill cap securely.
  8. Check for Leaks and Final Steps
    • Start the motorcycle and let it idle for a minute, then shut it off and wait a few minutes for oil to settle.
    • Inspect around the drain bolt, strainer bolt, and oil filter for any signs of leakage.
    • Check oil level via the sight glass or dipstick (as applicable). Top off if necessary.
    • Wipe away any spills, reinstall the skid plate if removed, and properly dispose of used oil and filter by taking them to a recycling facility.

Important Tips and Model-Specific Notes

  • The 2021 GAS GAS EX 350F shares its engine platform with KTM and Husqvarna 350s, so online guides for those models also apply, but always check for minor updates and confirm torque specs in your official service manual to protect your warranty and avoid engine damage.
  • Always use a new crush washer to prevent leaks—don’t reuse the old one.
  • Be careful with oil filter orientation—the wrong direction can cause oil starvation and catastrophic engine damage.
  • This model’s sump requires exactly 1.0 liter of oil when an oil and filter change is performed. Overfilling or underfilling can impair engine function.
  • Genuine parts and recommended oil are best for engine life and performance.
  • Change oil and filter at least every 15 hours of riding or sooner in extreme conditions, as per the factory recommendations.

Why Change Oil on Schedule?

  • Fresh oil lubricates, cleans, and cools the high-revving engine better than old, dirty oil.
  • Routine maintenance ensures engine longevity and optimal performance for your investment.

MotoSport.com Service Commitment

This how-to guide is proprietary to MotoSport.com and tailored to your 2021 GAS GAS EX 350F. For further support or to order OEM oil change kits and parts, trust MotoSport.com for the fastest and most reliable service in powersports.

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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.