Our Joker has been going 16 years, full time live aboard use.
Chlorine will kill the rubber, soften and expand it.
Paper can lodge in the corners and create a permanent set.
Mineral oils will soften and increase ability to permanent set.
We lube with kitchen grease (bacon fat etc) We do not use paper as it is unhygienic to "store" or dispose of, bad for the labia, and the ocean and never leaves you clean.
hose serves as a bidet.
Once in a while, we squirt some acid down there, or if we use acid for other purposes (Muriatic, Ospho, Vinagar, whatever) we dispose of it down there, with a 10 minute soak time.
We have counted the strokes to flush the pipes on our manual and the seconds on our electric
(Raritan Crown 1 1978 model) and make sure that we flush it clear.