Pressure Gauge Mustang

car trouble oil pressure. help?

Just another issue with my ford mustang. ever since I had the oil changed (could be a coincidence) the oil pressure gauge has been reading low. the oil is full, all the caps are tight, and the engine sounds fine. I took it back to the oil change place and they checked it out and said that nothing they did could have caused the issue. So I'm stumped, and I'd like to avoid taking it to a mechanic for like the 10th time since I bought it . also the gauge reads normal when I first start it up but as it runs it gradually drops, and when I accelerate the gauge sometimes climbs. please help I'm not experienced enough to know whats going on. thanks much.
it did drop to the red zone once. thats when i brought it back to the oil change place. And the also said they put the right oil grade in. the same weight they put in last time I had it changed there.

Hi,
It could be that whoever changed your oil put the wrong grade in the engine. If they used an oil that is too thin you could possibly have the problem you describe. Especially as the oil pressure was okay before you had the work done and that the pressure drops as the engine warms up, making an already possibly thin oil even thinner with the heat.
I'd be inclined to have the oil changed somewhere else and make sure they use the correct grade as stated in the owners handbook.

Hi, Just read your addition, it could be that the oil pressure sender unit, (the sensor for the oil guage that screws into the engine block), is at fault. If the guage dropped to zero and the engine didn't sound like it was starting to make a lot of noise, (a sign of no oil pressure), then I would suspect the sender unit. This is not an expensive repair and can be changed by a mechanic in a few minutes.

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