I would like to add an oil pressure switch (*not* sensor) to my 1985 300D.

The oil pressure specification per the FSM is no less than 3 bar (gauge) / 43.5 psi (switch) at operating temperature idle.

Of course, one can spend an eternity online looking at the almost limitless number of oil pressure switches available for the world's vehicles. The trouble is this: With the rare exception, the psi rating is not provided because few people care what it is. They just want to make sure that they select the replacement switch that fits their car.

So, my inquiry:
How to find out the psi rating of a given oil pressure switch? If I show up at a run of the mill auto parts store asking for a generic oil pressure switch rated 45 psi, could they know? How else might I either find this information or find a source online? And I assure you, I've looked a lot recently.

Thanks for any guidance on this-