>oRecordSet.OPEN([Select * From c:\test\mydbf Where mydbf.test1 = "Old Value"],oConnection)

You did not assign a the CursorType and LockType properties to the recordset. The recordset defaults to ReadOnly.

oRecordSet.OPEN(source, connection, cursortype, locktype, options)

oRecordSet.OPEN("Select * From c:\test\mydbf Where mydbf.test1 = 'Old Value'",oConnection,adOpenDynamic,adLockPessimistic)