  We examine the effects of the Rastall parameter on the behaviour of
spherically symmetric static distributions of perfect fluid matter. It was
claimed by Visser [Physics Letters B, 782, 83, (2018)] that the Rastall
proposition is completely equivalent to the Einstein theory. While many authors
have raised contrary arguments, our intention is to analyze the properties of
Rastall gravity through variation of the Rastall parameter in the context of
perfect fluids spheres that may be used to model neutron stars or cold fluid
planets. This analysis also serves to counter the claim that Rastall gravity is
equivalent to the standard Einstein theory. It turns out that the condition of
pressure isotropy is exactly the same as for Einstein gravity and hence that
any known solution of the Einstein equations may be used to study the effects
of the Rastall dynamical quantities. Moreover, by choosing the well studied
Tolman metrics, we discover that in the majority of cases there is substantial
deviation from the Einstein case when the Rastall parameter vanishes and in
cases where the Einstein model displays defective behaviour, certain Rastall
models obey the well known elementary requirements for physical plausibility.
These empirical findings do not support the idea that Rastall theory is
equivalent to Einstein theory as several deviations in physical behavior are
displayed as counter-examples.
