>>372883970
Repair box is better than buying oil.
Using the oil you find in the radius is better than selling it to offset repair box costs. Maybe save it for a gun with expensive repair costs or a lot of damage.
Don't bother trying to repair magazines yourself, just box them.
If you loot extra TP and ramrods you can leave them in the radius to create a little repair stash for keeping your weapons in the blue.