Soaked the sender overnight in WD40.  Started the engine and brought it up to running temperature and the sender came right out.  Thank you!

Most oil light sending units I deal with can be removed with a special socket designed for that purpose.  Oil pressure sending units however require a wrench close to the threads.  Here are pictures of the 3/8” drive socket I have for removing oil light sending units.  Vise grips or a pipe wrench gripped around the outside diameter of the sending unit could also be used.
 

 
 

Lorena, Texas (South of Waco)

X2! WD-40 is not a penetrant, it's a Water Displacer. Use PB, Liquid Wrench, something that says "penetrates" on the can.

Spray the heck out of it with PB Blaster, try tightening it a little too, sometimes that actually breaks it free, then try counterclockwise.......I got mine off not too long ago..........Good Luck !

Have You ever tried to remove one of those Plugs that have been in the block for Years? Easier to get the Sender out of the Block.

  

There are more oil galley plugs long the driver side of the engine. Use one of those and leave the stock sender as is.

Will do.  Thanks!

Phil I would soak it with Penetrating Oil Wd 40 or similar. Let it sit and soak overnite. Then You might also try a little Heat by letting the motor run up to operating Temp.

  

I am replacing the idiot light and stock temp gauge in my 292 Thunderbird with Stewart Warner Gauges.   The temp gauge and sender went in with no issues.   The stock oil pressure sender is another matter.  I can't budge it with a wrench and I'm afraid I'll strip the outside of the 9/16 nut holding it in.  Anyone ever have this problem?  How do I get the thing out of the block?