Is your range hooked up to bottled gas (LP) if so it could be the moisture from the LP gas. If not call Matt Schutte at Bluestar 800-449-8691

I would treat the grates just like a cast iron frying pan and season them in a slow oven. You will find directions in the link below. First heat your grills and get off that sticky surface. Wipe it down with dry paper towels, when it can be handled but is still warm and wash hot in soapy dishwater --not the dishwasher, wash them by hand. Then season them and--well the site tells you how to clean and season and keep cast iron seasoned. http://whatscookingamerica.net/Information/CastIronPans.htm

The confusion is in the word seasoning in this application. OK it's not a wok or a cast iron pan that needs to be properly seasoned but here's Bluestar's recommendation: This is from the BS web site..."Your ring grates, top grates and burner heads may darken over time with use. This is normal. TIP: To prevent your burners from darkening at an uneven rate, rotate the ring grate and top grates between more and less active burners. BURNER CLEANING Ring Grates and Top Grates TIP: Clean spills as soon as possible to prevent sticking and build up.  When burner is cool, remove the ring grate, top grate and center filler grate (30” models only).  Wash in hot, soapy water. Rinse well and dry thoroughly to prevent rusting.  Handle gently to prevent nicks/chips, which can lead to rusting TIP: If you have a nick or chip you can season the area to prevent rusting. Nicks or chips are not covered under warranty.  Put corn oil or other high smoke point oil on a paper towel and rub onto rusted area.  Wipe away excess oil and replace the part on the range. Do not submerge the burner grates in water for extended periods of time. Prolonged exposure to moisture may cause rusting.  For heavy soiling, use a commercially available oven cleaner. Follow the cleaner manufacturer’s instructions. Make sure the cleaning chemicals do not contact any stainless steel or painted surface on your appliance.  Reinstall grates in cooktop and make sure they are seated properly, and do not move unsteadily from side to side". So, BS says it's OK to hand wash or DW and they also use the word "season" so this is maybe why it's a bit confusing to some. It's not seasoning in the traditional sense but oil on these grates will keep them looking good over the life of the grates, IMHO. This isn't that different from keeping your backyard BBQ grates from rusting, same principle.... Here's a tutorial for cleaning, this is just informational.... cleaning your bluestar grates

My grates are black, and when they look a little goey I toss them in the dishwasher. And boy that does the trick they look like new again. I have heard (don't quote me) that this can cause them to rust. I wonder if this would be the case with SS grates. Mine are some black metal, not sure what they are made of. Bosch Range. ~boxerpups This is from Good Housekeeping Magazine Ask Helouise Is there an easy way to keep burners from getting grimy? -- Elizabeth Malvey, Wakefield, MA If you cook, there's really no way around it -- but you can give burners a thorough cleaning. Start by wiping grates and burners with a damp sponge. Remove grates and soak in hot, soapy water for 30 minutes. Add a teaspoon of ammonia to the sink water to help loosen the grime. Scrub them with a stiff brush to remove any remaining gunk. To minimize future messes, keep an eye on pots so they don't boil over.