I have a 1988 E150 Conversion Van with 260,000 or 360,000 miles on it.I know this is the original engine because this has been in the family since new.When I am on the highway with or without a load on the car hauler I tow the oil pressure is through the roof.I run 10w40 motorcraft oil and always have.It gets the 3,000 mile oil change like clockwork.The gauge drops slightly at stop lights but never goes low and it reads even higher during winter months and last September my oil cooler line sprung a leak on the Pa turnpike and I saw the gauge dropping and quickly shut the key off and drifted to the side of the road which saved the engine so I know the gauge is working but is it correct?I have included a photo of the gauges while driving so you have an idea of where it's reading.This photo was taken hauling an empty trailer on a open highway,we had been on the road for 2 hours when I took this so the engine was up to normal operating tempature and the speedo wrapped as far as it will go Radar detector/jammer running and the gauge is way up.Should I buy another gauge or is this correct?

 

its really just a fancy idot light. it gives the average person some insight on engine function. if you want actaul PSI readings you will need a different gauge. But yours seems normal so i would leave well enough alone.

 

install a mechanical pressure gauge. thats the only way you will truely know whats the pressure is.

 

I would check the actual pressure just for information sake.

There are often variations in sending units, but it would be very unusual for you to have a problem with the gauge. A failed gauge usually just reads nothing.

 

There's a sending unit near the oil filter. They do go bad and it's easy to change out. Now there are 3 types mentioned here:
1. A stock "switch" sender used for many years in Fords. It was designed to snap "on" at a minimum PSI, read mid-range, and never read anything else as long as the PSI was above a minimum. It is so useless.
2. A "gauge" sender, which actually varies its output with pressure. It looks identical to #1.
3. A mechanical gauge, which may require replacement of the stock sender or some funky rearrangement at best. There is no sender, it actually runs a pressurized oil line up to the gauge head. Honestly, I respect the usefulness of a numbered reading but I don't like these due to routing issues and the slight risk of damaging the hose and leaking hot oil under the dash.

If you get a replacement sender make sure you get the "gauge" type, #2. This is usually what you'll get at a parts store.

People talk about problems with the dash's voltage regulator going bad and mess up the gauge readings. However nothing looks odd about the other readings so I don't know if I'd suspect that.

Isn't 10w30 the recommended oil? Not like 40w's gonna blow it up though.

 

In 88 it probably still has a variable resistance sender, not a switch. The switch is small and short, while the variable sender is longer and fatter, so there is a difference between the two visually. I'm sure it is as correct as low and high can be .

 

get a good gauge soon
if the factory unit is a true gauge then the pressure relief
valve may be stuck in the oil pump
if so then you could blow out hoses or filters
have seen several fords do this