Oil gauge

[Jeff mctruck]

I have a 2011 avalanche, my oil gauge is fluctuating between about 25 and 40 mostly reads 40 when in lower gear, it's also running like it's losing power when the gauge reads lower, my battery gauge has also began to lower during a steady drive on hwy, I'm baffled at both gauges doing this, was wondering if anyone knows what might be the cause of this, I also have the proper oil level and recent oil change but this might have been going on for two or three months I only drive my truck on the weekends, I went on a recent trip and thought I might not make it back but I did so it's to the garage I guess for sure.

[CamGTP]

The voltage gauge will always vary, the computer is in control of how much charging is required. It can range from 13 volts all the way to 15 volts at any given time. If it's dropping to less than that you may have a problem to look at. A scanner is a better way to see vehicle voltage too, they are more accurate compared to the cluster.

 

Oil pressure can also vary but all your readings you described are within spec for oil pressure. Cold idle at 45-50psi is good, 25psi at hot idle and 30-40psi at hot cruising speeds. Full throttle should see it jump up to around 45-50psi as well. There is an oil pressure relief in the oil pan that limits pressure because of the AFM system.