My 1993 f250 5.8 started losing oil pressure when i bought it it was on the "n" on the temp gauge. When i went to change the oil i got talked into running full synthetic in it. A week later it started dropping more. At start up it is barely on the "n"on then it dropps a little more and untill it warms up it sounds like a lifter. Does anybody have ideas? It has 209,000 miles mostly highway.

 

From what I have seen those 5.8s were not a bad engine. Good workhorse.
You will probably get mixed reviews an using synthetic this late in the game.
I can only speak from personal experience and I use full synthetic in everything I have.
With that many miles a piece of foreign matter might have got into one of the lifters and sometimes it will leave just as quickly.
If you are concerned about the oil pressure , it might be a good idea to check it with an actual gauge and see what it really is.
Of course you could always pull the valve cover on the side you hear the noise loudest and double check that there is nothing out of the ordinary with the rockers.

 

Thanks hanky. I was told to try a 1/2 quart of transmission fluid to try clean the lifters. Whats your opinion? Im trying to keep from pulling the pan to replace the oil pump as i have dropped the pan on a older one and it was not easy.

 

I have added a quart of trans fluid to a few different engines with "stuck" lifter(s) and it did work. I did not suggest it here due to the mileage, but if you want to try it , it beats taking everything apart to clean/replace it.

 

flushing out all the sludge that's already in the engine is the first thing I would do. I've used diesel fuel about 1qt. with the rest oil in the one that I had. you just can't rev up the engine if you do that the risk of your engine blowing up is quite a bit higher at a high rpm so just let it idle and you'll have to change the oil four or five times to get rid of the fuel. and if that doesn't bring up the pressure then you'll have to replace the pump.