Can a used car dealer be fought?

I totally understand "as is-no warranty." However, the salesman assured us that the car was in great shape. He agreed to change 2 front tires & have the oil changed. He sent the car to an outside shop for the oil change, & that place did not put oil back into the car, which we picked up & drove! We returned the next day to report problems & this has been an on going issue for 5 months now. The engine is damaged beyond repair through no fault of ours! It now stands that the dealer has offered to trade for another car of equal or lesser value, of which they have none in stock currently, of course. I really just want my $$ back so that I can go elsewhere. Will I have to file through small claims court?