my s70 is 1998 turbu 2000cc i haven't changed the trnsmisaion oil for long time then i got the fault light and the shift arrow was emmeting..i checked with volvo garage i got the massage lock up funtion..and they erased the lights..then the same fault came back.. i changed the trnsmisaion oil and the arrow light went off..after 100km the 2 light came back and arrow light went off after one hour..do i have to change the transmission oil again as i put 4.5 liters only