The autometer gauges have no low pressure warning, and the best place to put the sender seems to be under the altenator.

I assume the sender "outputs" a resistance proportional to pressure. WHat is to stop me using a high impedence thing (like an opamp, current mirror etc...) to look at the signal from the sender and then using that as a (variable) threshold to trigger the oil warning lamp?

Shouldn't cost more than 50p or so to do, then I have all the functionality back