Low idle and oil pressure fluctuating

[Jtschweier18]

Ok. So I just changed the oil in my '01 s10cc and now my oil pressure gauge is fluctuating and it idles low (at about 500 rpm). Does anyone have any idea whats wrong?

[HenryJ]

What weight oil? How many quarts did you use? Did you check the oil level again after the filter was full?

[Jtschweier18]

I used 10w-30 and 5 quarts. I haven't checked the level again since I have ran it, so that could be the problem. I just got home so I'll let the truck cool down and then go check it again

[HenryJ]

Four and a half quarts should have been enough. Five will not hurt.
Minimum oil pressure can be very low. When hot some fluctuation may be normal. If you are not hearing noises and you still have some oil pressure, chances are that you will be fine.
If yours is a high mileage engine and you live in a warm climate, you might try some 15W/40 Rotella. While primarily used in diesels, it also carries ratings for motorcycles and gas engines. I really like it around here.
Be sure to use a good quality oil filter when you do the changes. It does make a difference and is not the place to save a buck.

Another thing to consider is if the oil pressure sender is beginning to fail. It is a pressure diaphragm and can fail. Check to see if it is leaking. It might need replacement?

[Jtschweier18]

Sorry I haven't gotten back sooner. The oil level is fine. When I first start the truck the oil pressure and rpm's are where they should be but when I put the truck in drive the rps drop to 500. The only problem with the oil pressure gauge is that when I brake it will drop to around 25-30 instead of the normal 45.

Is it just the oil pressure sensor that is starting to fail that is causing this?

[HenryJ]

I don't know your mileage. It may be that things are getting a little loose. Minimum oil pressure is 6 psig at 1000 rpm, 18 psig at 2000 rpm, 24 psig at 4000 rpm.
I would say you are well above that.
Try checking the sender for leaks and heavier oil if you are worried.
Like I said, if it isn't making noise and has oil pressure, you're probably fine.