I have heard of people using a very thin coat of vegetable oil, but honestly I have no clue lol.
I have a RedSea skimmer. Works great! Cup connects very tight. I always fight with it to get cup off.
so, after many times dumping cup in sump, on me, on the floor etc. I realized I had a habit of remove the cap on the cup before I tried to remove the cup. In hind sight - kind of feel dumb lol. Now I use one hand to hold cap on, and with other hand pry between cup bottom and skimmer neck to slowly guide cup off and not make a mess. Takes about extra 15 seconds.
point being- I made adjustment to myself instead of the skimmer. It would really suck to poison the tank for something that maybe rethinking it might have a different solution.
I do not know that in your specific case there is, but just saying explore all options first, sleep on it, Re- assess the situation and maybe there’s some Work around that’s Better then adding something your unsure if can cause harm.
idk lol. Just my two pennies
HAPPY REEFING!