Polyethylene is hydrophobic so it can only be combined with hydrophobic solvents mineral oil i.e. hydrocarbons. The term "homogeneous suspension" is not correct. A suspension is a heterogeneous system consisting of solid particles distributed in a liquid medium. Apparently, by the term "homogeneous suspension" you mean a thermodynamically and kinetically stable suspension. Without surfactants, the suspension of polyethylene in mineral oil can be improved by adding polyethylene oligomers. The more viscous the suspension, the more stable it is.