i am not sure whether there is a screw which we can renew the grease like subaru's absorber.
and whether the absorber we have is servicable or not.

assuming your talking shock absorber here?

ya.

I don't see anything on my old stock shocks or the mazdaspeed shocks that would allow added gease.

thats sad. all i can do is to spray anti rust into the shock allowance to make the sound go away.

They probably could be, but isn't worth it. You can buy Koni etc. for what it would cost you.

btw, serviceable shock = rebuild the internals, and there's no grease in a shock absorber, either that was a gas nipple or a greasable bushing, the RX-8 shock bushings do not need grease