I do get some oil in a few of my tubes. Nothing like you are getting. And I have thought about using some Hylomar under the tubes. I have used it elsewhere and like it a lot. But I kinda figured that if it would have worked, someone else would have already been there/done that.

If you decide to try some non-hardening sealant under the tubes, Hylomar would be at the top of my list to try. Permatex used to make version of it, but they discontinued it. The original stuff is expensive and a bit of a pain to get a hold of.

www.amazon.com/Hylomar-Universal-Non-Setting-Silicone-Jointing/dp/B07NJHZJQQ