Could someone tell me if 0 to100 psi. oil pressure gauge will work with 0 to 80psi sender. By mistake I bought 2, 0 to 100 gauges to replace the existing gauges that are 0 to 80 psi.

You will need the 100 psi senders to work properly with the 100 psi gauges.

Dozer,
Keep in mind that the sending unit will have to match the actual gauges that you have. A short sweep 100 psi gauge will use a different sender than a full sweep 100psi gauge. An Autometer gauge will use a different sender than a Stewart Warner etc.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

It will work but it won't read accurately.
Eddie

If they are the same brand and amount of sweep, the gauge will read 25psi when you really only have 20, 50 when you have 40, and 75 when you have 60psi.