Preheat oven to 350°F. Grease a 10-inch Bundt cake pan; set aside.
In a medium bowl combine the flour, baking soda, and salt; set aside.
In a mixer fitted with the whisk attachment, whisk together eggs and sugar on high speed until fluffy, about 3-4 minutes.
Reduce the speed to low and add the oil slowly until combined, then add the butter, and mix until just combined.
Add orange juice and zest and mix until combined.
Add the flour mixture and mix just until combined. Be careful not to overmix.
Spoon the batter into the prepared Bundt cake pan. Bake for 55-60 minutes or until the cake is cooked through.
Remove the pan from the oven and allow it to cool for 30 minutes.
Once cooked, tap the sides of the cake pan and then turn the cake pan over, and out onto a cooling rack positioned over a piece of wax paper or parchment paper.
In a small mixing bowl, mix the orange juice, rum, zest, and sugar to make the glaze.
Pour the half of the glaze over the top of the warm cake. Allow it to site for 5 minutes, to soak in, then pour the remaining glaze over the cake.
Transfer the glazed cake to a plate, slice, and serve.