The Al Ain Oasis is approx. 159 kilometres away from Abu Dhabi. With a car it will take approximately 1 hour 40 minutes to reach Al Ain Oasis from Abu Dhabi via the Al Ain Road/E22. Alternatively, you can take a taxi, however, the charges are quite high considering its a long journey.
One of the affordable options is to take the RTA Bus from Al Ghubaiba Bus Station in Dubai to Al Ain Central Bus Station. A one way trip from Dubai will cost AED 30 and it will take approximately 2 hours and 55 minutes.