If it's a newer year Focus I'd say it's letting you know it's gone longer than the recommended mileage to change the oil. My BMW assumes 6000 miles is the preferred mileage to change the oil, but its recommended to change the oil sooner in my opinion. Clean oil makes engines last longer in the long run.
replace driver seatbelt
The exclamation light, on your Ford focus, is a reference to the oil needs to be changed. The light can be reset by changing the oil.
A Ford Focus needs anywhere from 4.5 to 6 quarts of motor oil. The Ford Focus was fist produced in 1998.
A four cylinder 2009 Ford Focus hold 4.5 quarts of oil.
you are low in oil and you need a service
According to the 2002 Ford Focus Owner Guide : ( 5W-20 ) engine oil is recommended
In the oil pan, in the engine.
if it is a new ford focus then no, alot of new cars have regulators on them.
No
diesel
Motorcraft oil 5w20
Remove oil pan