In oils, the 2 numbers are as follows (or reasonably close)
0w, 5w, 10w, etc... are the "cold viscosities" (the "w" stands for "winter" not "weight"). It's a standard that says that when cold, the oil flows at some rate down to xº. So a 10w will flow at temps down to 0º and a 5w will flow at temps down to -15º and etc... (made up numbers, but you get the idea).
The second number is the viscosity when hot. The hot viscosity isn't the flow rate or thickness of the oil, it's due to the polymers in the oil that have expanded and increased the viscosity (increasing it's shear or something like that). So a 40 weight acts thicker than a 30 weight

So I don't know that you'd want/need to change the __w number, but you may want to change the second number to something larger.

What's interesting is that the Driven oil people used to have a chart that said something like "if your bearing clearances are xx, and your expected oil temperatures are yyº, then you are likely going to want to use ##w-## as a starting point for your oil viscosities."

I didn't embed because this image is huge
https://cdn.speednik.com/powerautorax55/wp-content/blogs.dir/1/files/2022/04/what-i-learned-today-bearing-clearances-vs-oil-viscosities-2022-04-04_12-49-04_516744.jpg

Except that his truck idles at 600rpm, so that means that 11psi at idle is over 18psi/1000rpm.

If you connect your sensor/switch to an air regulator, you can adjust the pressure and see where it opens/closes.

Hate to say it but it sounds to me like the bearings are getting thin.

To prepare myself, I’ve been looking at oil pump replacement and engine replacement.

The oil pump is not in the oil pan, but behind the timing chain cover and chains. A lot more involved. But something I could do. The pump is about $300 or $400, but as long as I’m in there, you want to do timing chains, ramps, etc.

An engine swap, would take longer than I would like to do by myself. I would probably have somebody else do it with a crate motor by Ford. The motor would be about ~$6000 plus labor.

This is my last vehicle, so if I could get another 233k miles out of it, it would be worth it

I ordered a tune that gives the ability to increase the idle, correct the speedo for tire size, a little more power, etc among other things. I’ll increase the rpm’s by 100 increments and see if I can get to a steady 15 psi at idle. I know it’s putting a Band-Aid on it, but hopefully buys me some time.

That is true, but the rule of thumb applies more to the high end. He is VERY low on idle oil pressure, and possibly lower than he knows...symptomatic of a serious engine issue.

Personally, I would NOT change the oil pump unless it was easy. That repair sounds like a lot of effort for a 'hope' repair. I'd be looking for a crashed vehicle, or a known good junkyard engine. And a tune that changes the idle rpm is a band-aid that won't help long term. The engine should have sufficient oil pressure to idle. Period.

I lean to the 'thin bearing' comment from JD.

Before I did the oil pump I'd pull the pan and look at a bearing.

Are you thinking worn rod bearings or main bearings or both? Would it be beneficial to replace the rod bearings with std if possible?

For used motors, there were problems with 5.0 engines before 2013 and they are not compatible after 2015, so the best engines to use are 2013 and 2014. That narrows down the candidates considerably. I was doing a search yesterday, and engines were going from low 2000 to 3000. While less than a crate engine, by the time I replaced all the wear parts I wanted to with new, it would probably add 1000 and I would have an engine with unknown history.

And a factory crate motor would likely last a LONG time compared to used or aftermarket rebuild.

The crate motor has a 3 year unlimited mileage warranty. Lakeland Ford sells them for $5800. I’m going to call and see what the cost is to install it.

I would guess worn main bearings, but that's a long way from a 'diagnosis'.

I'm not sure of how much you 'need' the truck, if it were me I would bypass the sensor and drive it, but have a mechanical gauge (anything without a transducer) in the cab.

I would also monitor the idle pressure and switch to a thicker oil as needed. You may get a lot of miles out of it, it's low, but obviously it's not fatal, at least not so far. That annoying shut off feature has helped you.

From those numbers, it does seem that a crate engine is the best value. I'm used to $1,000 engines being available. Not any more I guess.

Hi
I think lifting the idle speed and trying some thicker oils are good options before investing in a new / crate engine.
Other ideas:
Can rod and main bearing shells be replaced with the engine in place ?
Any pressure relief valves in the oil circuit that could be causing the problem ?
Cheers

I’m in construction, so I need a truck every day.
The digital oil pressure gauge is on the A pillar and super easy to see. On my next oil change, I’ll go with a thicker oil.

I called the Ford dealer in FL with the engine for $5800 and they don’t have any. And there are none in the pipeline. He gave me the name of a Ford dealer in Maryland that had three of them in stock. I called them and the price is $6200. I asked the service department there, how much it would cost to install the motor and they said $5000 to $5500. I think I would take a week off and do it myself.

Looking at the official Ford website, it says the engine engines are unavailable. I looked at used engines again and they are about $3000 plus shipping,with a minimum of 100K miles. I think I’ll buy the new crate engine and keep it for the future.

^^^ I’ve just started reading, but it looks like the rod bearings can be replaced, with the engine in place. I did think about replacing the oil pump with a high volume pump and replacing the rod bearings, but that’s a heck of a lot of work and a big gamble, for something that may not work. The crate motor looks like the best idea.

I bumped the idle to 825 RPMs, and that’s got the oil pressure at 18-20 psi.

That sounds good to me. That engine may run like that for another 50k miles.

^^^ I hope so!