How to Change the Oil in a 2010 KTM 85SX

Shop parts for a 2010 KTM 85SX Dirt Bike.

Changing the gear oil is one of the most important maintenance tasks you can perform to extend the life of your 2010 KTM 85SX. Proper oil changes ensure your transmission and clutch operate efficiently, preventing premature wear and costly repairs. This guide, proprietary to MotoSport.com, will walk you through each step for this specific model and year, with important call-outs relevant to the 2010 KTM 85SX.

Tools & Supplies Needed

  • Socket set or T-handle wrenches (ideally metric, as KTM is an Austrian brand)
  • Torque wrench (capable of measuring 20 Nm or 14.8 lb-ft)
  • Oil drain pan
  • Shop towels or rags
  • Magnetic oil drain plug (OEM or aftermarket, if equipped)
  • New crush washer/seal ring for the drain bolt (recommended every change)
  • Funnel
  • Full synthetic 15W/50 gear oil (Motorex or AMSOIL recommended by experts and the manual; use only high-quality synthetic oil, never cheap variants)
  • Measuring container (for accurate refill)
  • Pliers (for snugging fill caps as per KTM recommendations)

Preparation

  • Start with your bike on a stable, flat surface using a stand to keep it upright. This ensures an accurate oil level measurement when refilling.
  • Warm up the engine for a few minutes. Warm oil drains faster and carries away more contaminants. Be aware: hot oil can cause burns—use caution.

Step-by-Step Instructions

1. Remove the Oil Fill Cap

  • Locate the oil fill cap on the right side of the engine. Loosen and remove the fill cap. This allows the system to vent and oil to drain more quickly and fully.

2. Identify and Remove the Oil Drain Plug

  • Find the oil drain plug: it's the large bolt under the brake lever, on the right-hand lower side of the engine. Place your drain pan underneath.
  • Using your socket or T-handle, remove the drain plug. Allow the oil to empty completely into your pan. Be careful not to drop the drain plug into the pan—oil can be hot and messy.

3. Inspect and Clean the Drain Plug

  • Wipe the drain plug clean. If equipped with a magnetic end, check for and remove any metal shavings—tiny bits are normal, but an excessive amount may indicate internal wear.
  • Replace the crush washer/seal ring on the drain plug to ensure a proper seal and prevent leaks when reinstalled.

4. Reinstall the Drain Plug

  • Thread the plug in by hand to avoid cross-threading. Tighten lightly with a wrench, then use your torque wrench to tighten to 20 Nm (14.8 lb-ft) as specified. Over-tightening can strip threads in the aluminum case.

5. Add New Gear Oil

  • Insert a funnel into the fill port. Pour in the specified amount of oil: 0.8 liters (800 ml) of high-quality full synthetic 15W/50. Motorex or AMSOIL are the recommended brands for KTM two-strokes, never cheap or non-synthetic oils as this can impact performance or cause damage.
  • Install the fill plug and use pliers to gently snug it tight–KTM documentation recommends this to prevent loosening under vibration.

6. Check the Oil Level

  • With the bike upright and level, remove the oil check bolt/level screw (see your manual or side of engine–usually a smaller bolt below the fill). Oil should barely begin to dribble out when the proper level is reached. Top off as needed.
  • Reinstall the check bolt and tighten securely.

7. Final Checks

  • Start the engine, let it run for a minute, then inspect around the drain plug and fill cap for leaks.
  • If you find oil drips, recheck that the drain plug and fill cap are tight and that the new crush washer is seated properly.
  • Proper disposal: Take the old oil to a recycle center—never dump oil on the ground or down drains.

Model-Specific Notes and Call-Outs

  • 2010 KTM 85SX uses a fairly small oil capacity (0.8L); overfilling can damage seals and underfilling risks gearbox wear. Always measure carefully and check the level screw after refill.
  • Only use top-quality full-synthetic oil, such as Motorex or AMSOIL. This bike's transmission and clutch design demand superior lubrication and temp stability—avoid budget oils.
  • Check and clean the magnetic drain plug every service. Excessive metal debris is a sign of abnormal wear and should be monitored.
  • This engine uses a gearbox oil, not a standard four-stroke engine oil. Never mix hydraulic clutch fluid oil with gear oil; clutch fluid (Motorex Kupplungsfluid 75 or SAE 10) is separate and fills/purges differently.
  • Inspect the drain plug sealing surface and replace the crush washer every oil change to prevent leaks.

Why Change Oil Regularly?

  • Prevents premature transmission and clutch wear
  • Improves shift quality
  • Removes metal particles from gear/bearing break-in and use
  • Ensures internal parts are properly lubricated and cooled

Conclusion

  • Keeping your 2010 KTM 85SX's gearbox oil fresh is crucial for performance and longevity. With the right tools, quality oil, and attention to detail, this maintenance is straightforward and well worth your time. MotoSport.com has all the KTM-specific supplies you need for a pro-level garage job–even at home.

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Shop Oil Fillers and Drain Plugs for a 2010 KTM 85SX Dirt Bike.

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.