I finaly got the little plug out of the top of the block by the dis and installed my aftermarket oil psi gauge there. I also reinstalled the stock sender switch above the oil filter.

well the stock gauge seems to be pretty much right on with the after market gauge. when the aftermarket gauge read 30psi the stock gauge showed 30psi.

well today I added 1/2qt of Lucas oil stabilizer. Im not using it as a bandaid, its just my engine has almost 200,000 miles on it and had a rough life till I got it and I wanted to put some thing in that would coat the internals for a little added protection.

any way after I added the Lucas my oil psi increased as I figured it would, but what is puzzling me is I get a 5psi higher reading from the stock gauge than I do the aftermarket at all times now.
is it actualy possable the pressure is a bit higher at the bottom of the block where the stock sender unit is, and lower at the top of the block where the aftermarket gauge connection is?

 

no one has any clue why this may be??

 

My stock one always reads a little higher then my aftermarket one installed in the china wall.