If you mean that only 5mm of oil is showing on the dipstick, though, you need to add oil NOW before driving it anymore.
All dipsticks have lines at the top and bottom marked "E" and "F". You want to get it right up to the "F" line. How much depends on how large your engine is. At least 1-2 quarts, maybe more. Don't be like me, my car has an oil leak, and even though I put in oil all the time, I didn't put in enough, and I had to buy a new engine.
Not enough, period. Its not like the fuel tank, if it runs out you fill it up.
Some cars have only hash marks on the dipstick, the marks at the end of the dipstick is the low range, marks closest to "handle" end is the "full" range, that is where the oil should be. Use caution when adding oil, never overfill. If the oil is in low range, then generally one quart is needed. If more than a quart is needed add a little at a time, checking the dipstick every time.
There is no way to tell from that information - no way at all
Well luckily for you the answer for this is the same regardless of what you're driving (since you didn't mention it).
Actually that's not true - not by a long shot. Not every car/truck takes the same amount of oil.
Just put more in to make sure you are in the safe range, why does it matter how much is in there if you know you need more? Just add it.
