Technology has evolved, so that you no longer need to impress your neighbour with the plume of smoke pouring from your truck or tractor
by RALPH WINFIELD
Some of us remember when we looked at the colour of engine oil on the dipstick and then rubbed it between two fingers to see if it felt okay – with not too much soot (carbon particles) in it. Those two criteria determined if it was uncontaminated enough for additional miles or hours of use.