There are two that are sold side by side at Lowes. Make sure no one mixed them up. This type is safe for nitrite / rubber o rings !
This is what I use for years with no problems :
https://www.lowes.com/pd/Danco-Grease/1092167That leak: reviews always talked about this problem with the 406 and fluvals smaller filters . One leak area has always been with the type of clamps used . Too weak and get weaker with age , sucks air and leaks water out. Some leaks squirts out from an area settles somewhere else making hard to find where it's truly leaking. Like trying to find a roof leak on your house , travels all over. Problem never were you think it is. The clamp area , water hits the back side of it , goes up lands on top filter , that fix is a piece of air line split to apply tension to clamp / seal.
There are just too many parts in that head on the 406 many things to leak !
See the video for total "cleaning and maintenance" breaks it down very well !
There are "several" videos on the leaks with the ( 406 ) . Some have very simple fixes !
https://www.bing.com/videos/search?q=fl ... ORM=HDRSC3