The LV Strip Trolley makes a stop at Oasis but it only goes as far as Mandalay Bay then you have to transfer to another Trolley. You can buy a day pass ($6.50) but it is only good for the day (not 24hrs).
IMO the Trolley service is too slow and we couldn't count on it. 50 minutes from Oasis to Mandalay Bay is too long. Should be 10 minutes! (ok, maybe 1/2 hour with all the stops) One night we arrived early at a trolley stop and waited 30 minutes past it's scheduled time before giving up.
The "Deuce" bus service was much better. A 24 hour pass was $5.00. We used the Deuce for getting to and from the main part of the Strip and only used the trolley to get to and from Oasis.