I have a 2003 Mustang GT all stock with 92K miles on it. I use Pennzoil Ultra Platinum 5W/20 oil in it with WIX filters. The engine is very clean internally and has been carefully maintained and runs well. I decided to install a (real) oil pressure gauge. I installed a Equus mechanical gauge with 270 degree wide sweep. On cold start idle I see 80 psi. If I jazz the throttle just a bit it goes to 90 psi. After it warms up, it idles at about 15 psi. Driving at 55 mph (1600 RPM) it's at about...

Oil pressure behavior on 4.6