(Thread title was edited to make it easier to find in the future - hope that is cool)
Nobody has greasier, oilier cats than we do. They get a bath every single week because their hairless skin (they are Sphynxes) gets ultra-greasy.
We use a shampoo our vet recommended.
Shampoo for dogs, cats and horses.
I'll be honest though, when we have run out of it, on a few occasions we have used a bit of Dawn dishwashing liquid and never noticed any reactions. Our cat baci has bad skin just as an FYI. Seems lots of other people on the Net also use Dawn (hey they clean ducks with oil all over them in the commercials)....but I hesitate to recommend it (as it's a human product) when I feel the Virbac is superior and known to be safe.
Hope that may help