oil temp triggered relay

first of im not sure which forum to post this into so this seems most likely but please move it if needed :) i want to install an oil temp gauge into my car and have a relay triggered when the oil is upto running temp my understanding of the temp gauge is that it is triggered by an increasing or deceasing resistance from the sender. any info on what i could use to measure this resistance and then trigger a relay ? thanks allot guys KarlD6-In Car Solutions

A voltage sensing relay. IE - a circuit that switches at a certain voltage. There are many such circuits using comparators (LM3900 etc) or op-amps. You may need to consider input filtering (an RC circuit, ie, a small cap across the (comparator/op-amp's) input, and maybe hysteresis though that may be unnecessary.