How to Change the Oil in a 1990 Yamaha XT350

Shop parts for a 1990 Yamaha XT350 Dirt Bike.

Regular oil changes are essential to keep your 1990 Yamaha XT350 running smoothly and to prevent engine wear. This step-by-step guide—exclusive to MotoSport.com—will walk you through the process, detailing all the tools needed, the steps required, and specific details that XT350 owners need to know.

Tools and Supplies Needed

  • Socket set (including 12mm for the drain bolt)
  • Oil drain pan
  • New oil filter (Yamaha genuine or compatible aftermarket)
  • New engine oil (Motul 3000 4T 20W50 or SAE 10W40/20W40, type SE or better)
  • Replacement sealing washer for oil drain plug (Aluminum, 12 x 16 x 1.5mm recommended)
  • Funnel
  • Clean rags
  • Gloves (optional, but recommended for cleanliness)

Preparation

  • Start the engine and let it idle for a few minutes. This warms the oil, allowing it to drain more easily. Do not let the engine get too hot. A warm engine helps but avoid burns. Use caution removing any components.
  • Place the bike on a level surface and secure it on its kickstand or a bike stand.

Step-by-Step Procedure

1. Remove the Skid Plate (if equipped)

  • Some XT350 motorcycles are fitted with a skid plate. If so, remove it using the appropriate socket or Allen key to access the engine's drain bolt easily.

2. Remove the Oil Drain Bolt

  • Locate the oil drain bolt underneath the engine. Using your socket wrench (likely 12mm), loosen and remove the bolt. Be sure your drain pan is positioned directly underneath to catch the old oil.
  • Let the oil drain fully—this can take several minutes. Wipe away any spilled oil.
  • Specific call-out: Replace the aluminum sealing washer each time you change the oil. The recommended size is 12 x 16 x 1.5mm. This helps prevent leaks and ensures proper sealing .

3. Remove and Replace the Oil Filter

  • The oil filter is typically mounted on the right-hand side of the engine. Use the correct socket to remove the cover bolts.
  • Gently remove the oil filter cover. Some oil may leak—position your pan accordingly.
  • Remove the old oil filter and discard it. Wipe the filter cavity clean with a rag.
  • Install the new oil filter in the same orientation as the old one. Pay attention to the spring and O-ring—ensure they are either in good condition or replaced as necessary .

4. Reinstall Drain Bolt and Oil Filter Cover

  • Once the oil has finished draining, install a new sealing washer onto the drain bolt. Reinstall the drain bolt and tighten securely, but do not overtighten–refer to your owner's manual for proper torque specs.
  • Reinstall the oil filter cover, tightening the bolts evenly. Be careful not to pinch the O-ring to avoid future leaks.

5. Add New Engine Oil

  • Remove the oil fill cap (located on the right side of the engine). Position your funnel and pour fresh engine oil into the engine.
  • The correct amount for an oil and filter change is 1.4 liters (1.44 US quarts). For an oil change without filter replacement, use 1.3 liters (1.34 US quarts) .
  • Recommended Oil: While Yamaha originally specifies SAE 20W40 Type SE motor oil, modern alternatives such as Motul 3000 4T 20W50 mineral oil or SAE 10W40 can be used depending on your climate .

6. Prime the Oil System (Unique to XT350)

  • The Yamaha XT350 features a crucial oil bleed/priming procedure after oil and filter changes to avoid dry starts:
    • Locate the oil bleed bolt on top of the oil filter housing.
    • Loosen the bolt and kick the engine over several times (with the kill switch OFF) until oil seeps from the bolt hole. This removes air and ensures oil reaches the engine internals .
    • Retighten the bleed bolt once oil appears.

7. Check for Leaks and Oil Level

  • Start the engine and let it idle for 1-2 minutes. Turn off the engine, allow the oil to settle, then check the oil level using the dipstick. Adjust as needed.
  • Inspect around the drain bolt and filter cover for any signs of leakage.
  • Reinstall the skid plate if you removed it.
  • Dispose of the used oil and filter responsibly—take them to an approved recycling facility.

XT350 Model-Specific Tips

  • Oil filter priming is essential. The XT350 does not have an oil light, so priming prevents potential damage from starvation after changes .
  • Drain bolt torque should not be exceeded, as the aluminum casing can strip easily–use a torque wrench if possible.
  • Sealing washer should be replaced every oil change for a leak-free finish .
  • Recommended oil type (Yamaha's spec: SAE 20W40, modern alternatives: SAE 10W40 or 20W50 for warmer climates) . Always use motorcycle-specific oil.

Conclusion

Changing the oil in your 1990 Yamaha XT350 is a straightforward maintenance task that, when done correctly, will enhance the longevity and performance of your dirt bike. Remember the model's specific need to prime the oil filter chamber and always use the right type and quantity of oil and a fresh sealing washer for best results. For original equipment and high-quality replacement parts, trust MotoSport.com for all your Yamaha XT350 needs.

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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.