Pressure is Pressure right? Or is it? Pascals Law? Physics 101?

I used the the search function to no avail. Can I use a fuel pressure gauge as an oil pressure gauge or is the difference in density between gasoline and oil a problem in getting an accurate measurement? But wait, oil and gas can mix therefore is there a difference in density? I use to know this stuff... Thanks in advance js

 

Liquid is non compressable. As long as the fluid gauge reads in the range it will work.
If you have a 40 psi fuel system be sure to have suitable line to the gauge, that could be a disaster.

You are better off and safer to have a sender and electric gauge with fuel pressure that high.

Oh yea, efi is off topic here.

 

Thanks. I am looking to run a 0-10 fuel pressure gauge (which matches all the other gauges) as an oil pressure gauge for a Model A.

 

Oops how did I get that mixed up.
Same pricipal though, it will work.