Hi, really need help.
I have a 1980 300TD, first one I have owned. Been doing a bunch of work on it getting it sound to drive.
The oil pressure is very low when I first start the car. Comes up to about 15 when idling, and when im driving it goes way up to almost the top of the gauge.
Is this normal? I don't know but do not want to ruin the car.
If not any ideas of what i need to do or how to check it? I did change the oil and filter Rotella 15/40 and new WIX filter, was worried maybe I got a bad filter or something so I even put another new one in.
Please help if you know the answer and if this is normal.
Thank you so much for everyone's help on here.
Shawn

 

Thank you both so much, I was really scared so last night i pulled the small pan checked the oil pump which is good, my engine is really clean inside the screen is clear. Just in case I cleaned the pressure relief valve I think its called and worked it to make sure nothing was clogged inside it. Im going to go get mobile 1 and another filter today. I will stick with that from now on.
Really appreciate all your help. Diesel is new to me so im learning quick.

 

Did you change the two the 6mmIDx10mmODx2mmW O-rings that are on the bottom of that long tube that is in the Middle of the Oil Filter Cap? When worn or hard they have been know to decrease the idle Oil Pressure.

If you want to reduce Engine wear even further ask about ForcedInductions Bypass Oil Filter setup.

From research done by Members of anther Forum the NAPA 1385,WIX 51385 (info from the WIX site) claims filtration down to 32 nominal microns. Comes out as the poorest filtration compared to the below.

Mann 27 nominal microns in the Full Flow Section

Fram 24 nominal microns in the Full Flow Section

Mahle 22 nominal microns Full Flow Section

Baldwin P102/Hastings LF380 (US made) 18 nominal microns Full Flow Section and the Full Flow section is larger than the stock Oil Filter. and the upper bypass section is 15 nominal microns.
Baldwin and Hastings are parts of the same company but for some reason the Hastings Filters sell for less.
I bought some of the Hastings Filters and compared them to the few pics of the Baldwins I have seen and the appear to be the same Filter.

The Pruolator and the STP Oil filters seem to be from the same company are Made in India and the central tube inside is not even sealed. It is just sort of loose in there. I would avoid either of them.

Some People who have had low hot Oil pressure issues have had their idle speed lower that the minmum spec.

 

Yes, I did change both the o rings on the long metal thing that goes down the middle of the filter. I saw something on them on line so I got a bunch and figured I would just change them with each oil change.
Next oil change I will use better filters, your information has really helped me a lot. I am servicing everything before I really drive it to far, just to make sure it is all up to par. Has been a chore but has kept me busy. I still havent got the climate control working yet bet the thing under the hood, I inspected and it doesnt have any cracks but I can hear air leaking under the passenger side dash, so I thing I probably have an air leak under the dash going to what I think they call the amplifier. Havent had a chance to check it out yet, but im getting there.
My oil pressure is back to great after cleaning the valve in the oil pan and the inside of the engine looks very clean with no sludge or build up, since I dont have any prior reciepts on the car I do not know what was done to it, but looks like they did change the oil often.
If there is anything you can think of that I should need to do, please let me know and I will put it on my list and get it done.
Thank you all so much for your help with my car.

 

"My oil pressure is back to great after cleaning the valve in the oil pan"

Were you speaking of the Screen at the bottom of the Oil Pump? As I am not sure what Valve you are speaking of?

 

I still wish the OP would have answered.

 

Evidently I did not read post #3 where he said "Just in case I cleaned the pressure relief valve I think its called and worked it to make sure nothing was clogged inside."

And, I focused on the later post where he said "My oil pressure is back to great after cleaning the valve in the oil pan"....

Since I know that his Oil Pan does not have A Valve I wanted a better description of what He did clean.