  We propose a new theory of second-order viscous relativistic hydrodynamics
which does not impose any frame conditions on the choice of the hydrodynamic
variables. It differs from Mueller-Israel-Stewart theory by including
additional transient degrees of freedom, and its first-order truncation reduces
to Bemfica-Disconzi-Noronha-Kovtun theory. Conditions for causality and
stability are explicitly given in the conformal regime. As an illustrative
example, we consider Bjorken flow solutions to our equations and identify
variables which make a hydrodynamic attractor manifest.
