  We perform a post-Newtonian (PN) solar system analysis for Palatini $f(R)$
theories considering finite volume non-spherical planets and with emphasis to
$f(R)$ functions that are analytical about $R=0$. First we consider the
Will-Nordtvedt parametrized post-Newtonian (PPN) formalism, from which the
metric is shown to depend, in general, on terms not covered by the standard PPN
potentials. Hence, a full analysis of the PN equations of motion is performed.
From the latter we conclude that, apart from redefinitions on the internal
energy and the pressure, which cannot be constrained by solar system tests, the
center-of-mass orbits are the same as in general relativity. We discuss further
the physics of these redefinitions and use an argument to extend our analytical
$f(R)$ results towards some non-analytical functions.
