Engine?
Transmission?
Power Steering?
Differential?
Transfer case?
if you mean motor oil then it should start back up as soon as you fill it to the full mark on the stick ! if the oil pump is good then it should pick up the oil as soon as you start it !
After you check the level on the dipstick and make sure it reads to the full line, start it and check for leaks, then shut it off, re-check the oil level, add some if it has went below the full line, but don't overfill it. and drive on.
For engine
