Yeah my truck idles about 15 - 20 PSI and about 40 PSI at speed.As I have said before I am a mechanic by trade and thats normal for a car/truck in most cases.
I think the oil temp gauge gives a fairly close idea of oil temp. It is right above a gear that slings the oil right onto the sensor and the sensor is not touching the housing where it screws in. It may get some of the case temp but I think it's a good indication. It also gives you an idea of normal operateing temp and if that goes up , even if it is case temp you should be concerned.

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