take it to the Harley Davidson Service Dept.
Dot4
Start with 3 1/2 quarts. Run it and check oil level. Most of the time it will take 4 quarts.
App. 60hp and 65flbs of tq give or take depending on the tune , set up, and condition of your bike .
If you change the filter, you will need 4 quarts; however it may only take 3 &1/2 to fill. DO NOT ever over fill.
3 quarts
4 quarts
2.8 qts
take off primary cover and remove starter thru bolt
3 quart
No oil in crankcase in a Harley Big Twin. All FXR's take three quarts in the oil tank.
24 oz is what most take do not over fill or it will bust your seal