I did my first cook on my new YS640 2 weeks ago. Pork butt. I did the break in but the pork butt stuck to the grates and it was a little tough to get off. So what's the best way to season the grates so nothing will stick? Doing a brisket tonight and I hope it doesn't stick to the grates like the pork butt did.
That happens to pork butts sometimes even on really seasoned grates, so don't worry about it. The best way to season them though is to cook, cook, cook. That's the best method I have found. Time will season them nicely.
You can always spray or wipe a little canola or peanut oil on the grates before putting the meat on.
Some cooks like to use something like this: http://www.atbbq.com/store/show/frogmats.html
Frogmats are awesome. Really great for smoking cheese, fish, and small things like pistachios.