We show you step-by-step how to change transmission oil on a 2019 Harley-Davidson Fat Bob, from drain to fill, including tools needed to do the job. Though we used a Fat Bob, this process will be the same for most Harley M8 Softails.

How to Change Transmission Oil in a Harley-Davidson Milwaukee-Eight Softail

1.       Take right side panel beneath seat off in order to access dipstick/ fill hole using a 5/32” Allen.

2.       Snap off plastic cover beneath side panel.

3.       Remove dipstick with 3/8” Allen.

4.       Place drain pan beneath frame.

5.       Remove drain plug underneath motorcycle with 5/8” ratchet.

6.       Drain oil completely.

7.       Clean and inspect O-ring on drain plug. Replace if there’s any tears or gouges.

8.       Put drain plug back in. Tighten to 14 – 21 ft./lb.

9.       Measure 28 oz. of transmission oil. (We used Motul RSD 75W90 Synthetic Transmission Gear Oil)

10.   Using funnel, pour oil into fill hole.

11.   Hand tighten dipstick.

12.   Put motorcycle on jiffy stand and check oil level.

13.   Use 3/8” Allen and pull dipstick out.

14.   Wipe dipstick clean.

15.   Put dipstick back in.

16.   Remove once more and check fluid level.

17.   If level checks out, put dipstick back in and tighten down.

18.    Put side panel back on.

19.   Tighten down.