I have a 90 GT, for the past 6 months or so I have been experiencing bad oil pressure readings. My car is completely stock, no mods. While I am driving the car the oil pressure gauge jumps wildly up and down and when the car is at idle speed the gauge reads no oil pressure what so ever. The car has not been a daily driver for the past 3 yrs. I am at my whits end as to what may be the problem. The car has 150,000 miles on it and has always been well cared for. Could this be a oil pump problem? I have been told to use a heavier oil but I have had the car for 11 years and have always used the same oil. I have had the engine checked for compression and it is fine have had all the gaskets, head, oil pan, valve cover and any other gasket or seal that is possible. Could this also be a faultly gauge. Any suggestions would be helpful.
Thank you, Mathew

Don't get too worried it is probably a faulty gauge. I have an 89 gt and the oil pressure gauge reads 0 all the time.

try changing your oil pressure sensor. that's what's at fault most of the time. any auto parts store should have one.

Henry....

When I first bought my 88 GT the oil pressure would read low when first started then go to 0 at an idle.This worried me but the first thing I did was to obtain a manual (non-electronic) pressure gauge and remove the oil sending unit,to tee into the fitting on the engine. Start the engine,make sure there is no leak and read the gauge. Mine read 35psi at idle,50 at 2,500 rpm All very good readings, next I disassembled my instrument cluster and adjusted the needle on the guage to read correctly,key on enging off pull off needle and point it to 0. Mine was about 1/4 inch below that mark, now I feel better when I drive the car, knowing that I really do have good oil pressure.
So A: don't rely on the factory gauge's they are known to be inaccurate
B: If you follow the procedure of getting an oil pressure guage and it still reads low, it's probably engine rebuild time
C:To test an oil sending unit ground the wire going to the unit,(key on) watch your gauge,if it goes right up you need a new oil sending unit if it does'nt move its probably the guage or wiring related.
Hope this helps out, Frank.

[saleen'd]

I would get a proffesional opinion. My 90 lx had the same problem, up and down and then nothing at idle. About a week later it sounded like I was close to throwing a rod or barring. Turns out the oil pump was not working and 1 new motor later.......Get that sucker look at pronto!

[STINGREY]

more than likely your in need of the oil sending unit,notorious for going bad in this way.$20 bucks

[imarolltide]

i agree that it is probaly the sending unit,sometimes a bad sending unit will cause the needle to flicker just a little when you flip an electrical swit on the car(such as a headlight switch).just something you can check.

[GhostDog 5.0]

If you have access to a mechanical gauge, I'd test it to make sure it's running right. If it is, replace the sending unit. If it's really low, you could have a weak/worn pump or you dont even wanna know.

[maxxxxd]

Same symptom with mine a short while ago. Check the oil sending unit of the drivers side of the block. The old one is a huge bell-shaped fitting. The new one from Ford is a smaller black plastic top, but works and that's all that mattered to me.

It could also be the oil pump as well (worst case scenario)