how much oil needs to be in the engine to register a reading on the dipstick???

the guy said there was 3.5L of oil in the engine including the 1L i put in...... and then he added 1.1L and it was full at 4.6... he then drained it all and put a fresh fillter and oil in.... 3.5L in the engine and the dipstick is bone dry doesnt sound right to me
but yeah got a nice letter which will be getting delivered on wednesday