So , is it only Monsanto's product or are all generics included ?

Gasoline works well.

I've been mixing Image and Bayer Advanced Southern Lawn Concentrate Weed Killer with a little Dawn in a pump up sprayer and it works good, especially on that Khaki weed. I've about got the nutsedge under control but it takes some work.

What kind of weeds in what kind of grass? There isn't one that works for all weeds in all grass types. For broad leaf weeds I use something with 2,4-D and it is safe to use on most grass types. For grass type weeds it gets a lot more specific and some only can be treated with pre emergent. Weeds like nutsedge and kyllinga are really hard to get rid of and there are only a few herbicides available to the public.

To win the war on weeds you must first know your enemy and then know the weapons that are effective.