With electricity going to your idiot light system, but the engine not running, your oil light should come on because you have no oil pressure. It should go out a few seconds to a minute after you start up. Your water
temperature light should not, because the water
is not overheated. If your running water temperature is below boiling, you can test the sensor
by connecting an ohm meter across it and boiling the sucker on the stove
. Your electrical
should light up when voltage drops, so a test will depend on where it's set - most in cars trip when at rest, and go off when the alternator
The low RPM usually means fouling or over prop, if you have eliminated those, check your compression
, with the rough check being the quality of your exhaust
Change the oil!! Preferably do it with heated oil, but do it. "Tools over?" Is there an O-ring missing around the collar of the dip stick? It's a no-pressure situation, and it probably takes an unusual cant to actually spill oil.
Consider replacing the lights with gauges and the sensors with more than switches. It won't cost much, because automotive parts
for both. Gauges are for people who scan their instruments
and are interested in what is going on inside their engines. Idiaot lights are for....well, you get the picture.
Good luck with exploring it all. This is how you get to know your engine, and it can be a new friendship.