We study several cosmological models with Bianchi \textrm{VI}0
symmetries under the self-similar approach. In order to study how the
\textquotedblleft constants\textquotedblright\ G and Λ may vary, we
propose three scenarios where such constants are considered as time functions.
The first model is a perfect fluid. We find that the behavior of G and
Λ are related. If G behaves as a growing time function then Λ
is a positive decreasing time function but if G is decreasing then Λ
is negative. For this model we have found a new solution. The second model is a
scalar field, where in a phenomenological way, we consider a modification of
the Klein-Gordon equation in order to take into account the variation of G.
Our third scenario is a scalar-tensor model. We find three solutions for this
models where G is growing, constant or decreasing and Λ is a positive
decreasing function or vanishes. We put special emphasis on calculating the
curvature invariants in order to see if the solutions isotropize.Comment: Typos corrected. References added, minor corrections. arXiv admin
note: text overlap with arXiv:0905.247