Fluval 206 Gasket Ring. Whats Type Of Lubrication

[ShinySideUp]

I think it keeps the sealing ring supple; a hard ring is liable to leak.

 

[jonnyc88]

Found this thread on Google. I've just got a Fluval 307 and it was making "whoosing" noises so I did some quick maintenance.
I've put some PTFE/Teflon tape around the intake hose and also lubricated the O ring with...vaseline.
In the manual looks like this is a no-no.
Time for new O-ring...