Adjoint-Higgs breaking of SU(3) to SU(2) and U(1) ($SU(3)\to S(U(2)\times U(1))$)

For an adjoint vacuum expectation value proportional to $\mathrm{diag}(1,1,-2)$, the centralizer is $(SU(2)\times U(1))/{\mathbb{Z}}_2$. Four gauge bosons remain massless and four acquire a common mass. This differs from Fundamental-Higgs breaking of SU(3) to SU(2).