Not a night and day difference, but with temps now at -17C / 0F the oil temp is able to get to 88C / 190F without trouble. I'm monitoring the oil temp to make sure it doesn't get hotter than say 95C, but so far it has only gotten to 90C once. I can remove each cover independently so if needed I'll remove one or two. When the temp outside was mild last week, the oil temp was only 85-87C or 185-190F without the grill covers. I put them on once the cold weather rolled in.Have you noticed a difference in oil temps with your grill blocks in place?