Oil in Starter Motor

1989 Grand Marquis - Firestone recently replaced a starter motor for me and then two months later it failed again. I figured a bad starter. Firstone says the starter was soaked with oil and that it will happen again. They also said it is a fire hazard. Anyone had any experience with oil on/in the starter. Anyway to stop chronic oil leaks?

I may be too late but if this is a 5.0 litre there is a filter (screen) under your pcv valve that rarely gets changed or cleaned which causes pressure to build up in the crancase and cause oil leaks,check it out.