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  • Writer's pictureJohn Baker

How To: Harley-Davidson® Primary Oil Change

Updated: Jul 12, 2021

Periodically changing primary oil guards against chain, gear and bearing wear while helping prevent clutch slip for confident takeoffs. It’s a simple job you can do with basic tools and a little know-how. Here’s how to perform a Harley-Davidson primary oil change.


For this demonstration, we’re using a 2014 Harley-Davidson Softail Fat Boy Lo.


Tools you need for a Harley-Davidson primary oil change

  • Primary funnel

  • Drain pan

  • New O-ring

  • 5/8-inch socket

  • T27 torque bit

  • Socket wrench

  • Torque wrench

  • Primary cover gasket

  • AMSOIL Synthetic V-Twin Primary Fluid



  • Locate the primary-fluid drain plug, which is right below the primary case.

  • Next, use the socket wrench and T27 torque bit to remove the primary cover. There are five bolts; make sure you set them somewhere safe so you don’t lose them. Set the primary cover aside.



Drain the primary oil

  • Slide your drain pan in place, then use the 5/8-inch socket and socket wrench to loosen the drain plug. Remove it the rest of the way by hand so it doesn’t fall into the drain pan.

  • Next, replace the gasket on the primary case cover. You should be able to pull the old one right out. The new gasket should drop right into place, then set the cover aside.


  • Clean the drain plug and install the new O-ring. Start it by hand and then snug it up with a socket wrench and 5/8-inch socket. Set the torque wrench to 14-21 foot-pounds of torque and tighten the plug.

Fill the primary with oil


  • It helps to use a funnel designed for a primary case. Harley-Davidson Softails require one quart of primary fluid. Be sure to check your owner’s manual or the AMSOIL Product Guide for the correct primary oil capacity for your bike.



  • Once you’ve filled the primary case with fluid, double check the fluid level visually. The primary fluid should touch the bottom of the clutch plate.

  • Finally, replace the primary cover. After hand-tightening each bolt, use a torque wrench and T27 torque bit to tighten them to the proper setting. Your torque wrench should be set at 84-108 inch-pounds of torque. Remember to tighten them in a star pattern much like the lug nuts on a car tire.

That’s all there is to performing a Harley-Davidson primary oil change. Make sure you dispose of the used oil properly. For your specific bike, consult the owner’s manual for oil capacity and viscosity, or check out the AMSOIL Product Guide.




We submitted AMSOIL synthetic motorcycle oil and Harley-Davidson SYN3 oil to independent testing. Who came out on top? Find out here.



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