Fire Ranger: if the variable is measuring constant, then it's always right
. But it still seems that gauge is pretty much useless. It might be useful to know oil pressure in a high performance engine, but i can't see it in a 4-banger.
spankis: I'm going to use an LM34 temperature sensor for the ambient ($4). I've tested it in air and water seems to work just fine. Exhaust temp and oil pan temp will be high temperature (probably K-type) thermocouples that should work regardless of working fluid. I really don't want to mess with any of the factory wiring and don't plan on tapping any existing lines.
rwenzing: 300 is mighty warm. But it'll help me narrow down my selection. The k-type i was looking at are good to 1300 so they're a little much.