Oil Pressure and stuff

[Anthony the man]

Hello, I have a 1991 E350 7.3l IDi diesel. When I run the diesel in the drive way after about 15 minutes the oil pressure drops to the low low side of the meter on the dash. I do not have a oil pressure guage just that Idiot bar low high. I have been getting the bugs out of this thing slowly.

Engine has 167k miles on it. Where can I find a dip stick for the oil. Mine snapped off at the ring. Looked every where can't find one.

So in short what would cause the oil presure to drop from the middle of the guage to the low end after engine warms up. Oh whats the best oil to use too. What can I expect for MPG. Its an E 350 super duty van.
I have driven it about 30 minutes on the highway with no problems. No oil leaks or smoke out of exhaust. Car faxed before I bought it and it has been serviced regularly. Any info on parts, Maint, what do expect etc appreciated

[2000blackbeauty]

Go to your local navistar dealer for a dip stick....uh....about your oil pressure...try the oil pressure sender.

Question 1: After your engine is warm, does the oil pressure gauge return into the normal range?

Question 2: If you answered yes to Q1 does it return to low when you stop at a stop light or idle again?

Those senders are kind of a joke...all the gauge is an idiot light with a resistor and a needle. After your engine makes 7psi of oil pressure the needle will just settle out there somewhere and you feel all happy cuz it appears to you that you have plenty, when in truth you could be running 3250 rpm with 8psi and it would say you have plenty of oil pressure. lol. Unfortunately to me it sounds like you just get dangerously low oil pressure after your engine warms to operating temps? I hope this isnt the case. Good luck with the van dude.

[Phillip A.]

I would go get a cheap oil pressure gauge with numbers and hook it up to get your true oil pressure then go from there.As for oil I use dello 15w40 I have 225k miles and been using dello since day 1,and never had a engine problem yet.

[FordGuy100]

You can not trust the factory gauges. They are glorified idiot lights basically. For example, the oil pressure gauge your refering to is an on/off type of deal. When your truck has 8psi of oil pressure, the needle will move. When you go less than 8psi, it goes to no oil pressure. The needle moves only because of a little ohm resistance thing in the wiring designed to move it so it looks like your pressure is going up and down, but it actually doesnt show whats going on. 10 psi of oil pressure will read the same as 50psi on those gauges.

I would recomend to all to buy some real gauges, these will only show you if something is seriously wrong.

For instance my water temp gauge doesnt even get past the long line before the C for Cold, doesnt even cross that, and my water temp will be 190*