Thanks for the replies, but I meant adding crop oil along with some 80/20. I've always added a pint of 80/20 to the mix because I buy the cheapest gly i can find and don't trust the makers to put enough surfactant in it. But I got a jug of crop oil sitting there and have wondered if it will make the gly more effective to add some of it too.

Since I wanta kill everything, I doubt it will hurt. But is it just a waste of money to add both?

I've never added anything with my gly and i've always got a good kill. I add 80/20 to my 24d and clethodim, but never my gly. 2 quarts an acre on gly. No one can answer how many gallons because we don't know how many gallons it takes for you to cover an acre travelling about 5-6mph. Whats the gpm of your pump and nozzles? Best way to know is to calibrate it by filling your tank and seeing how many gallons it takes to cover one acre travelling 5-6mph. Mine takes about 16 gallons.

How long will gly kill? Meaning if I spray now, how long until I can plant safely?

I've always waited 2 weeks, but some of these guys plant immediately.

So how much Dawn soap are you guys talking about adding to it? I just got a 26 gallon sprayer.

Not that much. A few ounces tops.

Gly kills actively growing plants, by the roots. It won't hurt seeds. Thats the reason i tell people if your weeds and grasses have already went to seed, it'll kill the plant but all those seeds will be redistrubuted and will come up again.