I appreciate what you're saying Chas, but I would prefer to have a temp gauge. Engine management lights don't give you a clue as to whats wrong. For instance, on my truck the ABS warning light came on last week. I had to take the truck to DAF to have it put on the diagnostics computer, just to say one of the sensors had moved a bit (and had an 'air gap') and I had to push it in a bit. Cost £50 for the diagnostics and 2 hrs of my time (wheels off, brake drum off, brake shoe off, 2 seconds to push sensor in (!) and then reassemble). Everything is geared to having the manufacturer 'mechanics' (part changers more like) do the job for you at an astronomic price. Most dealerships are around £90/hr. How they warrant it I don't know!