If trading the car in, I wouldn't say a thing. The dealer isn't going to disclose it to the new owner (assuming they don't just send the car to auction). All they will do is use it as a reason to give you less on trade.
With a private sale, I'd definitely let them know. My old truck used just a little bit of oil during an OCI, but I still let the new owner know. He didn't mind.
With a private sale, I'd definitely let them know. My old truck used just a little bit of oil during an OCI, but I still let the new owner know. He didn't mind.