Stain problem on my coloured trousers.?

There's this really annoying stain on my nike max trousers I've tryed vanish oxy action with two washes and it ain't come out. It's a oil stain from motors it's everywhere on my grey nike trousers and it's reaaallllly annoying does anyone know a way to get it out without ruining it and with everyday household products help me as soon as possible please!! (100% polyester)