FLH 1999 - 2008 Adapter Key Installation Steps

Keeping Your Harley Running Cooler with UltraCool

The adapter key is a unique product offered by Ultracool. Its function is to stop the oil adapter from rotating when you remove your oil filter. Bikes from 1993 -2006 don’t have a part of the case so the Ultracool team devised a way to stop your oil adapter from rotating. Below are 2 pictures with the part of the case and without. Check yours before you start your installation.

Step 1

Remover oil filter and clean up filter mount. In the parts bag you will notice a 90 degree piece of metal referred to as an adapter key. If you have a bike from 1999-2006 you need to install this to prevent oil adapter rotation when changing your oil.

Step 2

Remove the 7/8” adapter in center of oil filter mount. Place adapter key so long tab fits in the hole of the engine case. Add a few drops to thread locker adapter nut and replace the center of adapter key as shown.


In the FLH 1999 – 2008 Oil Cooler Installation Guide you will notice steps 2-3 are removing your stock or old oil cooler. Now continue on with step 4 of the installation.