I'm with Comodave. Why spend money and effort on diagnostic tools when the easiest thing to do is swap wires and then senders to see which sender or gauge is a problem?
Of course it is possible that the oil pressures are in fact that different, but it's much less likely than an instrumentation problem.
Jim
In the expected case, checking the pil pressure with a mechanical gauge takes less effort that swapping senders -- it saves all of the time to disassemble and reassmble the likely good sender side.
In the unlikely case of confounding problems, it provides reliable ground truth.
$25 with free 2-day "to your door".delivery isn't much money or effort.
And the tool, used only occasionally, will likely last a lifetime. In the future there will be no extra effort or cost. It'll be free and on hand.
Even my most rarely used tools -- things like my cooling system.pressure test kit, exhaust gas detection fluid, phototach, SWR Meter, and thermal sensor have gotten loaned up and down the dock and used on a bunch of different boats, by the owner or myself
The only tools I have ever regretted buying were those that never worked, or broke or wore out early.
I just don't see the $25 as a measurable cost. The storage space is the cost ai feel at my end.
Most importantly, as someone who is super big on preventative maintenance, over time, I've introduced a ton of "maintenance induced failure" on my boat. I'll risk breaking something that is working just fine for scheduled maintenance -- but not for something unrelated. Nothing worse than starting with one problem and creating a second, maybe worse problem.
It might be different if the tool were hundreds of dollars or many days or longer away, etc.
...just my thinking.
My two cents.
