Hello my name is Lou.
yes its possible but what are the odds of the plug missing after WAL-MART changed the oil.????
its possible the plug was not missing or you would have seen oil leaking somehwere also its possible they did not refill the oil. i do insurance inspections from time to time and any time there is a engine malfunction from wal mart or sears or k mart its because they did not refill the dam oil.
the evac system is a vacuum operated caniter that pulls oil out through the dipstick. so whay are you paying them for a oil change to evac when they have to go under neath and change the filter anyways seems kinds retarded that they expect you to believe that they would take 25minutes to suck the oil out then pick the car up in the air anyway to change the filter. i think they are making it up. they may have the system but its only a benifit to european cars that have the filter mounted on top of the engine.hope this helps, sorry bout what happened,Lou.