I have a 2009 nightrain FXSTB.
24,000 miles (a few miles of rain and even some snow)

Not to long ago I took apart my bike to install a new starter clutch. During the process I noticed some rust gathering inside the holes where the oil enters the upper part of the oil tank. This was the first time I have exposed this part of the bike since purchased new.

I'm going to assume this is normal. I am also going to assume I shouldn't just put the bike back together without focusing some attention here.

Have you ever remodeled an old home? You tear into one project and pretty soon you are gutting the whole house!

Here is my plan:
Clean as much rust from the holes as possible. I have gathered a few rust tricks from my cafe bike project.
Treat the metal inside the holes with some type of rust inhibitor.

I know we have some skilled mechanics in the HD Forum family, so please let me know if I should be doing something different.

 

Had the same exact thing with my 2002 FXST, worked on it about a month ago. I had the oil tank removed because I was getting it prepped for new paint, so that made it a little easier to work on

I balled up/twisted a couple little pieces of blue shop towel and stuffed them as deep into each hole as I reasonably could. I then scraped away and tried to get as much off the surface as I could. After that I shot a couple layers of rust reformer. I let that dry overnight, then the next day put a couple coats of Rustoleum automotive primer (used it due to its dark color..not like you could see it down there anyway, but it's the thought that counted). Finally I put new oil line retainers/o-rings in there after I put it back together. Cheap insurance

Might be a better way to do it, but this is certainly better than it was before. I don't think I'll have any problems with it coming back