Even at our S&B we do not put ANY grease down the sink drain it goes down the toilet. Reason being 1) larger drain, 2) grease will congeal when it hits the cold water in the toilet form small gelled balls and then flush down with no problem. Got this from a plumber who said that if you must put grease down a drain do it with COLD water not hot. As to no food down the sink in the MH, we try to prevent this as much as possible without being anal about it. Food down the sink drain can and will cause the grey tank to stink as much if not worse then the black tank.