Renault Scenic loss of power,warning light and whining sound

Had the car for 2 years now and since the beginning the Orange Warning light has being coming on intermittently when Going uphill with a slight loss of power. The car has the well known air con fan fault and I was told that the warning light coming on was probably connected to this and wasn't a major problem. However today after a 200 mile trip the Warning light started to come on more often and then the red stop and oil lights came on and the car lost all power. The engine had not overheated, and I suspected maybe the oil was low so managed to crawl into a petrol station and top up the oil which was very low. However for the following 20 miles the Orange light stayed on , very little power (crawling at around 50mph)and there was a noticeable whining sound from the engine. My thoughts are that it may be the turbo (not sure why as I am an idiot when it comes to Engines!) but there was no noticeable smoke coming from the engine or exhaust. any help as to what this might be before I have the expense of taking to a garage would be very much appreciated....