Quote:
Originally Posted by Tcoat
So driving down the highway and you get a low oil pressure situation and your car just shuts down? OH sounds like a great idea.
If your low pressure light comes on it it either too late or no problem anyway. Shutting the car down automatically is the dumbest idea yet.
So when exactly is the ultrasonic device supposed to measure the level? The level varies with engine speed and temperature.
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There is an ultrasonic wave generator that measures the distance to the surface of the oil, continuously. You will recall compression and rarefaction waves from your high school physics (also useful to understand tuned headers, intake runners and variable valve timing) and SONAR from reading about WWII submarine warfare. Same technology.
The resulting signals are processed continuously and if the actual level drops below the factory preset safe level (obviously some distance below the low mark on an analog dipstick) the warning is displayed. Most will not display oil level at all to the driver unless certain parameters are met: parked level, engine off for x minutes and not too hot.
There are also microwave versions (a type of RADAR) and thermal types (oil surface temperature will be slightly hotter than the air above it.)