If it smells of burnt toast it is knackered & will need re-manufacturing or changing for another used one (as most seem to do). Don't waste you money on an oil change.(or it brown and smells of burnt toast)
It sounds like a temp sensor issue to me, there are probably more than one on the engine, one will be the guage & there may well be another for the ECU. I don't know for sure though never having had to look for it.