Try Cat Lube treats from Veterinarian's Best. They're chicken flavored, don't have petroleum, and most cats seem to like them (although sometimes you have to break them into small pieces that are easier for a cat to pick up). Most pet stores have them, or you can buy them online. They're made with psyllium (the same thing humans take!) And keep them away from plastic bags! Try throwing them a few fresh green beans - they spin entertainingly when attacked on a non-carpeted floor, which makes them seem worth tasting...