Install rubber bushings
Forum reader “tank_military” asked for advice on keeping a toilet seat tight for more than a few months at a time. Another forum member advised that he change out the plastic toilet seat bolts to steel. We think that’s just a temporary fix too.
Here’s a more permanent fix. Buy a toilet seat tightening kit (about $3) from a home center or through our affiliation with amazon.com. Remove the toilet seat nuts and insert the rubber bushings (Photo 1).
Install seat stabilizers
Then install a set of toilet seat stabilizers (Photo 2), such as Safe-T-Bumpers ($4 at amazon.com). That'll eliminate loosening caused by side-to-side movement.