We are testing the Delete Process Instance job so that we can develop a process maintenance plan. When executing the job setting only the "Finish Date To" parameter, the job actually deletes all process up to 3 AM on the day AFTER the date set for the "Finish Date To" parameter. This is undesirable behavior. This scenario has been tested in both CA PPM v15.1 and v15.4, with the same results.
It is working properly as it is taking Database timezone which in this case in PST and user's your account settings is in EST, so when user checks the instances via Administration->Processes it is deleting processes instances up to but not including 3:00 AM EST the next day.