there is hope for you. I've cleaned and lubed my own freehubs lots of times without taking them apart. If you remove the rubber seal along the inner face if it is there (Only the better freehubs use one) then you can flush out the freehub using solvent by dunking the hub in solvent then lifting it out. The solvent will fill the insides and then drain out when you lift the hub up. A soak for an hour and then repeated dunkings to flush the insides will remove any sort of grit and old oil. Following that a spray clean around the gap at the rim of the bearing cup with brake cleaner from an autoparts store will blow away any stubborn remnants.
If it is still crunchy then it is due to rust and there's nothing you can do about that anyway. The couple that I took apart that were rusty invariably had rusty bearing seats as well so even new balls would not last long. So if it is still crunchy get a new one.
Assuming it's now flushed and silky feeling the lube operation is just another dunking but this time you want to use a fresh mixture of some heavy oil like chain saw bar oil and solvent. For this I recomend lacquer thinner so it will evaporate sooner. Mix equal parts oil and solvent and use a smaller container so you don't need a lot. Dunk the hub, remove and spin a few times then dunk again, spin again. When it's fully loaded and spun lift and drain and then set end down on a paper towel to soak up what drains still. Let dry for a few hours and it should be smooth, and have a nice muted click to the pawls. The thicker oil will last longer.
Grease is not something you want in the freehub. Grease on the pawls will prevent then properly snapping out and engaging the teeth and you'll curse at how often it fails to catch or skips. Oil is what you want and even then just a thin coating of something that won't wash away with the first rain. Hence my own choice of chain saw bar oil. I've got freehubs that have 3 or 4 seasons of Pacific North"WET" rain commuting and they are still silky smooth.