2. Locate the hydraulic oil fill port. On a Case 4230, this is usually located on the left side of the tractor, near the rear axle.
3. Remove the fill port plug.
4. Use a funnel to add hydraulic oil to the tractor. The recommended hydraulic oil for a Case 4230 is Case Hy-Tran Ultra or a suitable substitute.
5. Add oil until the level reaches the "Full" mark on the dipstick.
6. Replace the fill port plug.