Volvo: Minimum Oil Pressure, 1993 945 Turbo with B230FT engine, oil pressure gauge, gf 1

Question
Greetings,

I want to add an oil pressure gauge in my wagon. I know the stock setup is a pressure switch only. If I were to get a sender and gauge, removed the stock pressure switch and thread the new sender in its place in the redblock, then I would lose the functionality of the in-dash oil pressure idiot light.

So... I can get a sender and gauge that has a built in warning (on/off) circuit for a given minimum pressure.  The supplier I am looking at has senders with warning circuits from 7psi to 30psi. What should be the minimum pressure applied on the sender before the warning circuit is closed, so i am warned of a low pressure condition?

Answer
Max,
The spec as per Volvo is
Oil Pressure [1] :    min 250 KPa (35.5 psi)


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[1] : at 33 r/s (2000 r/min), warm engine, new oil filter, and specified oil.

So then at idle it will be less. I think that I would go for a low warning of 10 psi. Unfortunately there is not a spec for at idle.

Oil specs per Volvo
Type    SG, SG/CD, SH(Motor Oil, API Service SG, SG/CD, SH; GF-1)

Above 0°F (-18°C)    15W-40

-4°to 104°F (-20°to 40°C)    10W-30

Below 68°F (20°C)   5W-30

Below 104°F (40°C), except 850   5W-40