Well, here is a good article on chain cleaning lubing where WD-40 is recommended, but then there is an addendum at the end indicating that it is probably not such a good idea for the O-rings.

http://www.webbikeworld.com/t2/motorcycle-chain-lube/#wd40

But now for a stupid question. I keep searching for a diagram of a chain that shows me exactly what the o-ring is. I assume that the round, cylindrical part that connects the outer plates of both sides of the chain is the bushing. Where is the o-ring(s)?

Pedal Till You Puke