Yeesh. Quite a tale. 
Are you sure you have the correct dipstick? Assuming you aren't the original owner, it's possible the original was lost and a mismatch was found simply to fill the hole.
FWIW, both of the vehicles in your profile have the M113 engine and share many things, including the oil capacity, 8 liters, or about 8.5 USQ.
So far as the oil level light coming on, I would clean the sensor connection and see if that helps. If not you'll have to replace the sensor...add that to the list, eh?
Good luck!
Are you sure you have the correct dipstick? Assuming you aren't the original owner, it's possible the original was lost and a mismatch was found simply to fill the hole.
FWIW, both of the vehicles in your profile have the M113 engine and share many things, including the oil capacity, 8 liters, or about 8.5 USQ.
So far as the oil level light coming on, I would clean the sensor connection and see if that helps. If not you'll have to replace the sensor...add that to the list, eh?
Good luck!