How to Change the Primary Oil on Vehicles

by Contributing WriterUpdated June 12, 2017

Your Harley-Davidson Vehicles 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 Vehicles time investment.

Under The Hood:

 How to Change the Primary Oil on an HD Street Glide

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.

Items you will need

  • Torx 40 socket

  • Socket wrench

  • 1 qt. primary oil

  • Primary inspection cover gasket

  • Oil catch basin or container

  • Towels or rags

 How to Change the Primary Oil in a 1996 Harley-Davidson Sportster

Park the Sportster on a flat, level work area with good ventilation. Start the Sportster and let it idle in place for three to five minutes. Stop the engine and let it cool for at least 10 minutes.

Mount the Sportster on a service stand to support it in a level, upright position. Place a drain pan beneath the larger portion of the primary cover on the left side of the motorcycle.

Loosen the drain bolt from the bottom of the primary cover, below the round derby cover, using a 5/8-inch socket and a socket wrench. Unscrew the drain bolt slowly by hand until primary oil begins to seep out from around the drain bolt threads. Pull the drain bolt away from the primary cover at an angle towards you to avoid being splashed by the draining primary oil. Allow at least five minutes for the oil to drain.

Pull the O-ring off the drain bolt and wipe the drain bolt threads and tip with a show towel to remove any debris. Screw the drain bolt into the primary cover by hand once the oil has drained completely. Tighten the drain bolt to 21 foot-pounds, using a torque wrench and a 5/8-inch socket.

Unscrew all five bolts attaching the round derby cover to the primary cover, using a T27 Torx socket and a socket wrench. Pull the derby cover and gasket off of the primary cover to expose the clutch assembly.

Pour 32 ounces of Harley-Davidson primary fluid directly into the primary. Stop filling when the fluid level is near the spring on the bottom of the clutch assembly. Wipe up any spilled primary fluid with a shop towel.

Reinstall the derby cover and gasket onto the primary cover. Screw the derby cover bolts into place until they touch the derby cover, using a handheld T27 Torx socket . Tighten the derby cover bolts in a crisscross pattern to 84 inch-pounds, using a torque wrench and a T27 Torx socket.

Remove the Sportster from the service stand, then lower it onto its side stand.

Items you will need

  • Service stand

  • Drain pan

  • 5/8-inch socket

  • Socket wrench

  • Shop towels

  • Drain plug O-ring

  • Torque wrench

  • T27 Torx socket

  • 1 quart, Harley-Davidson primary fluid

 How to Change the Primary Oil in an Indian Scout


Locate the oil drain plug and position the oil catcher pan below it. The plug is located underneath the left side of the motor. It can be found next to the primary dust cover.

Remove the oil drain plug with a wrench. Wait for the oil to flow into the oil catcher pan.

Examine the seal surrounding the oil drain plug for evidence of any damage. Look for indicators such as corrosion, cracks or a worn outer seal. Clean the seal with a white cloth to remove any excess oil or metal debris.

Locate and remove the primary engine drive inspection cover. Look for a rectangular panel positioned near the dust cover. Unscrew the screws using a screwdriver and remove the cover.

Inspect inside the engine drive shaft for corrosion and engine chain anomalies. Wipe away any excess oil using the white cloth.

Replace the primary inspection cover and reinstall the oil drain plug; ensure it is tightly fitted to the oil bin.

Locate the primary inspection port and remove the oil cap.

Pour 1 quart of fresh primary oil into the inspection port. Do not overfill the primary oil port.

Replace the oil cap on the inspection port and wipe away any excess oil.

Items you will need

  • Oil catcher pan

  • Socket wrench

  • White cloth

  • Screwdriver

  • 1 qt. primary oil

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