I am not "sold" on the concept of motor oil bringing them in. If they "are what they eat" then I don't want ANY that are attracted to motor oil. Others say diesel fuel. Were that the case, they should have eaten all of the lines on my tractor, which is situated on the property most days. They have not. Based on a statistically insignificant population of one property, observed over 20-years, I would say they don't like diesel or motor oil...it might have an adverse effect though, like keeping them away or keeping them nocturnal.