How to Change the Primary Oil on an HD Street Glide


Your Harley-Davidson Street Glide depends on three separate oil types to transfer power from the v-twin motor to the pavement: engine oil, primary oil and transmission oil. While changing the engine oil is a basic motorcycle maintenance skill, many new Harley-Davidson riders are often left in the dark when it comes to changing the primary oil. Fortunately, the process is fairly simple, requiring only a few tools and a minimal time investment.

Things You'll Need

  • Torx 40 socket
  • Socket wrench
  • 1 qt. primary oil
  • Primary inspection cover gasket
  • Oil catch basin or container
  • Towels or rags
  • Locate the oil drain plug and place your oil catch basin below it. The plug is placed under the left side of the motor, just below the primary "derby" cover.

  • Remove the primary drain plug with a Torx 40 socket attached to a socket wrench and allow the primary oil to drain.

  • Inspect the primary drain plug o-ring for damage, replacing the o-ring if necessary. Wipe away any metal shavings that may be attached to the plug's magnetic tip with a clean rag. Set the drain plug aside.

  • Remove the primary inspection cover, which is a rectangular-shaped panel located just before the derby cover. Remove the gasket from the primary inspection cover and discard.

  • Replace the primary drain plug, tightening it snugly against the primary cover.

  • Add primary oil into the primary by pouring it through the primary inspection port. This will take a maximum of 1 quart of primary oil. Do not overfill.

  • Place a new gasket on the primary inspection cover before re-installing.

  • Wipe away any spilled oil and dispose of used primary oil properly.

Tips & Warnings

  • If possible, consult a service manual for comprehensive details about this process, torque specifications and other maintenance requirements.
  • Start the motorcycle and let it warm up for a few minutes to help the primary oil flow better when draining. Be sure not to let the oil get too hot to prevent from getting burned.
  • If you do not feel that you can complete this project, have the work done by a qualified technician.
  • Do not over-tighten bolts to prevent damage. If possible, use a torque wrench to accurately tighten fasteners.
  • If the drained primary oil smells burnt, your Street Glide may have a damaged or faulty stator. Have the motorcycle inspected by a qualified technician immediately.

Related Searches


  • The Professional Motorcycle Repair Program; Professional Career Development Institute; 1995
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