Hi carmwade,
A car is definitely recommended for visiting Ojochal because it’s so spread out. if you’re planning to rent a car from the San Jose airport, we recommend Adobe. They’re a good company with reliable cars, plus we get a discount through them that could save you some money (more info here). If you’re getting from the airport to Ojochal some other way and just want a car to get around locally, we’ve had good luck with Hertz in Uvita. They are usually more expensive though so it might be worth looking into if Adobe is about the same price to keep the car for the whole trip, including to and from the airport.