Many relevant hints on the superconducting properties of a family compound can be derived from the behavior of the temperature and/or doping dependence of the superfluid density. Here we propose a transverse field muon spin rotation investigation of the superconducting properties of the optimally F doped La(1-􀀀x)Y(x)Fe(0.995)Mn(0.005)AsO(0.89)F(0.11) compound. In this system the substitution of La by the isoelectronic Y gradually increases the superconducting transition Tc from zero to about 30 K in the range 0 < x < 0.3. The aim is to measure the superfluid density, via the analysis of the muon linewidth, while Tc is increased. This will help to elucidate the behavior of the superfluid density in the oxypnictide superconductors and to clarify the presence of an expected quantum critical point.