Quite obviously your need for mouthwash should be assessed by your dentist as everymouth is different and has different requirements.
I should also say that I am not a big believer in the benefits of the slurp and swish mouthwash in general although it is a great addition in certain circumstances.
There are 3 different mouthwashes
1. antiseptic (savacol, OB tooth and gum care, listerine, amosan, and most other supermarket brands)
these contain agents that slow down and kill bacteria
2. bad breath mouthwashes (closys, freshen)
contain chlorine dioxide which kills bacteria that cause bad breath
3. fluoride mouthwashes (Neutrafluor)
These are used to strengthen enamel and slow down decay causing bacteria
If you are young (aged less than 30) you have no gum disease, very few fillings, brush your teeth with a fluoride toothpaste, drink fluoridated water and attend a dentist every 12 months then I would say no mouthwash.
Sometimes using a mouthwash gives people a reason to do less with their toothbrush and toothbrushing is much more important.
If you have had some recent decay and worried about your fluoride exposure then Neutrafluor 250 or 900 would be beneficial.
If you are over 30 and have had bleeding gums, gum pockets, and/or history of gum disease then using an antiseptic mouthwash (savacol) on an interdental brush such as piksters is very useful.
Bad breath is another issue. Closys is my mouthwash of choice in this instance
Do not allow your mouthwash to replace good toothbrushing technique or interdental cleaning