On the 1986-1990 models, the oil level screw (stock is philips-head) is located on the side of the primary cover, forward from the clutch cable mount and below the shifter lever. The Oil Drain Plug is located on the lower/rear of the left-side engine case.

On the 1991-1993 models, the oil level bolt is located at the rear of left engine case, rearward of the oil drain plug, also located on the lower/rear of the engine case.

On the 1986-1993 models, you will remove that oil level bolt while the bike is upright, NOT ON THE SIDE STAND (you'll need a helper or a lift). The proper oil level is when the oil is barely seeping out of that bolt hole.

If the oil level is too low, remove the primary chain access cover (used during primary chain adjustments) and add enough oil to obtain the proper oil level as described above.

On the 1994-2003 models, the clutch inspection cover (Derby Cover) is removed. The proper level of oil, when the bike is upright, NOT ON THE SIDE STAND (you'll need a helper or a lift), is when the oil level is just at the bottom edge of the clutch diaphragm spring. The Oil Drain Plug is located on the lower/rear of the left-side engine case.

Note that for 1994-later, the manual says “Verify that lubricant level is even with bottom of clutch diaphragm spring.” Not higher or lower, but even with the diaphragm spring. It also includes this warning: “Do not overill the primary chaincase with lubricant. Overfilling may cause rough clutch engagement and incomplete disengagement (or clutch drag).”

On the 2004-2017 models, the clutch inspection cover (Derby Cover) is removed. The proper level of oil, when the bike is upright, NOT ON THE SIDE STAND (you'll need a helper or a lift), is when the oil level is just at the bottom edge of the clutch diaphragm spring. The Oil Drain Plug was moved to the lower/rear of the Primary Cover.

If the oil level is too low, you may add oil through the clutch inspection cover to raise it to the specified level.

Oil quantity needed for a typical oil change (after the bike is warmed to operating temperature and then allowed to slightly cool) is between 28oz and 32oz.

Click on a pic to enlarge:

Primary/Transmission oil drain & oil site level bolts on a 1991 Sportster 1)	Primary/Transmission oil fill hole on a 1991 Sportster 2)

Primary / Transmission fluid drain plug on a 2001 Sportster 3)	Primary / Transmission fill and check site for a typical 1994-later Sportster (1994 example)4)