After the car cooled down you did start it and check if the blue smoke was still there? It would restart? Smell your oil to see if it burnt a little?
I really wish some young guy on site would engineer a very simple low cost system to enable a loud buzzer . So if either oil pressure dropped below say I bar or coolant temperature exceeded say 220 the alarm would trigger. It is my belief if simple and all fittings are incorporated in the kit for a reasonable price it would sell.
I would buy four kits myself as I am too casual about changing out rad hoses, belts, and those pesky oil cooler lines. I do inspect them from time to time yet that does not really mean they will not fail suddenly. There are many other things that can cause either oil pressure to drop or coolant temperature to rise quickly.
The cost of missing it and my thought is one easily could as a lot of people do are just too expensive to ignore. The essential strength of the kit is the individual could source out all the required odd parts. The design is simple. Perhaps I should ask one of my friends to take it on as it is overdue. I do not have time other than perhaps for getting a simple as possible design together.
When the buzzer fires believe me you are going to instantly look at your temp and oil pressure gauges. Possibly across north america one old mercedes diesel engine per week would be spared. Idiot lights are not good either unless extremely bright.
I fired a serpentine belt the other day on our toyota. In bright sunlight I did not catch the dim fault idiot lights very fast. Yet still caught them before the rad had boiled out more than a few cups of coolant. The time interval would have been a little more critical at highway speeds.