Just wanted to pitch in with a couple of comments that might help someone. As the title describes I have a 1998 F150 that the oil gauge needle started bouncing especially when I would come into a stop and then it will go back to normal after I would hit the gas. It was obvious pressure drop. As many forums suggested I checked the oil level, which was good and then switched out the oil pressure sensor. It was a cheap part so I decided to go ahead and just buy it and change it. After installation of the new sensor, the symptoms did not improve. I started to think back when it started to do this. The last I remembered was that it started doing it after an oil change at my local Ford dealership. I went to Autozone and asked to purchase a quart of motor oil to have handy in case I needed to add some more. The employee told me “oh you need 5w20 for your Ford”. Then I said “no my truck takes 5w30 motor oil”. He then said “no f150’s take 5w20“. I soon realized that the dealership had done an oil change and replace my oil with 5w20 which viscosity was just too thin. I did an oil change with the correct oil viscosity (5w30) and my problem was fixed. No more bouncing oil pressure needle at any point during any of my drives. I didn’t have to replace the oil pump or any of those major components that people may suggest. I know this was an easy fix however before you start changing all these parts (people are suggesting) make sure you do have the right viscosity because in my case it made a world of a difference. I hope this helps someone because in my experience in looking through the online forms I never saw this or came across a post like this.

 

5W30 was the original spec in 1998, but since then Ford has changed the spec to 5W20 and made it retroactive. That's why the dealer used 5W20. My 4.2 has 200k on it and I have used 5W20 in it since I bought it, and have had no oil pressure issues. I have no idea why you had this problem, but it's not normal. Perhaps you have abnormal engine wear from inadequate maintenance in the past?

 

i guess you are correct. I have no idea but oil change has solved my issue. Weird I know but glad it took care of my issue. It’s been 30 days and still doing ok.