Chevrolet Repair: oil pressure light, ac delco, oil sending unit

Question
ok my 95 caviler had no problems ran like it was new off the lot i have replaced and kept up this car very well on day i got lazy and had walmart do my oil change since then my oil pressure light comes on only after the car has been running for a long time and only will idoling it turns off when you press the gas pedal i was told that it could be the oil sending unit but i need help i don't want to start replacing stuff then have to junk the car theres no knocking the engine purrs like new what could this be
also walmart swears its nothing they did but it started the same day they changed my oil and there is oil in the car at the proper levels

Answer
Hi Eric,

In my experience, a low pressure light is not usually a sending unit malfunction.  We hope so, but usually it is indicating something.  Sending units can get gunked up inside and give faulty reading.  But more often the sending unit is bad if it is leaking oil.

How many miles on your car?  If may run great, but the pump is worn, or the bearings are worn.  You don't want to get cheap in the cars older age.  A few dollars saved now, and a lot of money spent later.  

Now, what happened.  Sounds like a cheap oil.  If it is too thin, it can have less pressure.  Breaks down too fast when hot.  Could be a cheap filter.  If it is not allowing the oil to flow through it, the pressure could be low.  

Bottom line:  Don't wait!!  Get the oil changed again, from a better place.  I change my own oil.  But I would take my own filter to the place.  The filter is soooo important.  They are all in it to make money.  The more cheap the parts, the more $1 or $2 they make, per car.  I use FRAM or AC Delco for your car.  Nothing else.  Left to the next oil change, and you could do irreversible damage to the motor.  

My philosophy is Keep It Simple.  If no problems, until the Walmart incident, then reverse the steps.  Go to where you usually go.  

I hope this works for you.  May have done some damage already.  May be a fluke and the pump is worn, or the bearings are worn.  Maybe the sending unit...but I am thrown by the fact that it happened immediately, and didn't happen before.  

Hope this helps.

C J S