How to Change the Oil in a 2018 KTM 250SX — MotoSport.com Guide

Shop parts for a 2018 KTM 250SX Dirt Bike.

Regularly changing the gearbox oil in your 2018 KTM 250SX is vital to prolonging engine life and ensuring reliable performance. This robust guide covers everything you need, including the tool list, every step of the process, and model-specific call-outs every 250SX owner should know before diving in.

Tools & Supplies Needed

  • 10mm and 13mm sockets (deep socket recommended for drain plug)
  • T-handle or ratchet wrench
  • Torque wrench (accurate to 20 Nm / 14.8 ft-lb)
  • Drain pan (large enough for at least 1 liter)
  • Funnel
  • Shop towels or rags
  • New crush washer for drain plug
  • Recommended gearbox oil (KTM recommends 0.8L specific SAE oil — refer to owner's manual for viscosity based on your climate)
  • Pliers

Step-by-Step Oil Change for 2018 KTM 250SX

  1. Warm Up the Engine
    • Start your bike and let it idle for 2-3 minutes. This helps the oil warm up, allowing it to flow and drain more completely.
  2. Remove the Skid Plate (if equipped)
    • Use the appropriate socket to remove the skid plate for easier access to the drain bolt.
  3. Loosen the Oil Fill Cap
    • Locate the oil fill cap on the right side of the engine. Loosen or remove it to let air flow in during draining, helping oil exit faster and more completely .
  4. Drain the Oil
    • Place your drain pan beneath the engine's drain bolt (bottom left side of the engine case).
    • Use a 13mm deep socket to loosen and remove the drain plug. Be careful — the oil may be hot .
    • Let the oil drain fully. Tilting the bike slightly toward the drain bolt can help evacuate lingering oil.
  5. Inspect and Clean the Drain Plug
    • Wipe the drain plug's magnet clean. Some debris on the magnet is typical, but excessive or shiny particles may indicate internal wear .
    • Install a new crush washer on the drain plug to ensure a tight, leak-free seal.
  6. Reinstall the Drain Plug
    • Thread the drain plug back in by hand to avoid cross-threading, then tighten with your T-handle or ratchet.
    • Use your torque wrench to tighten to 20 Nm (14.8 ft-lb) as specified by KTM .
  7. Refill with Fresh Oil
    • Insert a funnel into the fill hole. Pour in 0.8 liters of the manufacturer-recommended gearbox oil .
    • Use a flashlight (if needed) to check the oil level with the sight glass or dipstick, ensuring you do not overfill.
  8. Secure the Oil Fill Cap
    • Replace and snug down the oil fill cap with pliers for extra security to keep it from backing out during operation — a KTM-specific recommendation .
  9. Wipe Down and Dispose of Oil Properly
    • Wipe away any spilled oil, reinstall the skid plate if removed, and dispose of old oil responsibly at a recycling center.

250SX (2018) Model–Specific Call-Outs

  • This is a two-stroke dirt bike; only the gearbox oil gets changed, not engine oil as with four-strokes .
  • The factory spec is 0.8 liters of gearbox oil — overfilling can lead to excess clutch drag or leaks.
  • A magnetic drain plug is standard; always check and clean debris. Replace if the magnet is damaged or missing.
  • Changing the oil frequently (every 5-10 hours of use) is essential for engine longevity, especially when riding in harsh conditions.
  • Always use a new crush washer during each change to prevent leaks.
  • Use only KTM-recommended oil grades for optimal clutch and transmission life.
  • Refer to your owner's manual for torque values and lubrication specifications .

Pro Tips from MotoSport.com

  • If your bike's been tipped over or run hard, let it settle on a stand for a few minutes before draining the oil, allowing all oil to move back to the crankcase.
  • Always inspect the drained oil for metal slivers or unusual discoloration, which can indicate more serious internal wear.
  • Record oil changes in your maintenance log for warranty and resale purposes.

Changing the gearbox oil regularly on your 2018 KTM 250SX is quick, straightforward, and the most important maintenance for your two-stroke's transmission and clutch.

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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.