Lucky escape there mate!
It's running on it's own engine oil, probably a blown turbo but there are other causes.
Check the intercooler, it's probably full of engine oil. the turbo seals have gone and it's leaking oil, they all do a bit but eventually so much of it gets into the inlet that the engine ingests it, if the turbo lets go then it will run away and you are stuffed.
Other possible causes are a faulty crankcase breather, either letting oil be sucked out of the crankcase or blocked so that the crank gets pressurised and the oil return from the turbo is pressurised causing the turbo to leak. Check by removing the oil filler when it's running.
Important! do not drive it again until you find the cause, not only will it be expensive if it fails but also damned dangerous if you can't stop the engine.
Look on U-Tube for runaway diesel if you need convincing. it may be worth making sure you can disconnect the intercooler hose in a hurry, if you must drive it perhaps disconnect it first.
