My sump wasn't rusty, it actually disintegrated. Noticed an oil leak and the sump was so bad couldn't get the plug back in. I was lucky it didn't fall out. Was basically told thta it wasn't designed to be used all year round!! It was coated in ACF 50 which did help. I had changed from an 09 R1 to the S1000 and to be honest it was like new after two winters of riding. Lovely bike but hard work on track. looking forward to getting the blade on Knocky.
It is an incredible bike and would be fine if you ride a few thousand dry miles a year or strip the bike down For cleaning after every ride. But that's no me