They want to know the oil pressure due to the fact you engine supplies the turbo with oil, if your engine pressure is way down on start up then the turbo life expectancy drops massively hense the turbo breaking, if the engines fucked don't put a new turbo on it thats why they ask.
You need to take it somewhere or get a gauge, the pressure of my engine on start up is 80psi dropping to 25-35 psi warm/idle.