We have had our Broil King S520 for only 2 years and the cast iron cooking grids are rusted very badly.  The company needs to make a better quality grid and do a recall/replacement for these terrible quality grids.  The cost of replacement grids is very high considering they last less than 2 years.  The grill itself would be great if this 
grid problem was fixed.  Obviously, from the many other reviews, this is a very common issue.