Just noticed black smoke coming out of exhaust when going uphill. Also temp gauge goes up at same time then returns to normal. No loss of power, OK on flat and downhill, driven at a steady 60-65mph most of the time. Do you think its fuel related rather than engine oil which is still clean and correct level. Its a Fiat 2001 2.8JTD with 40k on clock. Any ideas?:helpsos: