Can I Put Mineral Oil In Cats Ears?

No, the only thing that should ever be used is an alcohol based product meant for ear washing. This can be purchased at your vets.
Oil cannot evaporate and it can trap bacteria in the ear, causing a severe infection.
In addition, it can damage the ear drum.

No, do not put mineral oil in your cat's ears.  This is not a treatment for any disease of the ears or ear canals.  It also does not help clean the ears.  If your cat has discharge from the ears have the cat examined by a veterinarian.  They will be able to determine if there is a bacterial infection, yeast infection, ear mites, or foreign body in the ear canal.  They can also prescribe appropriate medication and a safe ear cleaner.