Where is northstar engine oil sensor unit?
On a fitting right near the oil filter.
Usually it will take about 7 quarts on a Northstar V8. Note of interest...Some Northstars have a tendency to leak when full of oil. Because of this some Northstar owners only put in oil to the middle of the low and fill lines on the dipstick and this seems to solve that little problem. Other than that the Northstar is an amazing engine.