I have many cats they have hard black dirt in there ears. I clean what I can with cotton and babyoil. What else can I use. Is this ear mites.

Hi Momovsix! I just stopped by the site this morning before taking care of my errands.

You actually posted this in the wrong place. It should be under pets, cats.
But, I can answer your question. Yes, it sounds like ear mites. Usually babyoil and cotton work pretty well. But, if you have a lot of cats, they might be reinfecting each other. My suggestion would be to run down to your local pet store and pick up one of the medications that they sell for this. Ask one of the clerks if they have a reccommendation as to which one is the most effective to use on a large group of cats.

And, as an FYI between you and me, on Monday, make sure that all the litterboxes are cleaned out and that any kitty odors are minimized.;)