I have a 1991 Suburban w/350. It has 130,000 miles, original engine. I bought it last year. I'm not sure what oil was used but assuming it was conventional oil. I use synthetic in all my autos. Not long after I bought the truck I switched over to mobile 1 10w30 full synthetic. I'd say it was not more than a month after that I noticed my oil pressure gauge maxing out.

Here's whats happening:

Start the engine pressure is fine. Start driving and the pressure tends to jump up really high, close to 60psi. At highway speeds the gauge maxes out.
Slow down, or take my foot off the gas, or take my foot off the gas and back on again and it MIGHT drop back below 60.

The engine runs great. Doesnt smoke, doesnt burn oil, doesnt run hot.


So what could be causing the oil pressure to jump up so high?

I dont drive the truck that often and am worried about driving it long distances because of this oil pressure. But today I took an hour long trip, and an hour back, mostly interstate. The pressure stayed maxed out pretty much the whole time but the engine ran great.

Thanks for any help!!!!

 

Try putting in a mechanical oil pressure gauge to see if your gauge is accurate or not. You might just have a bad sensor, wiring or a bad gauge.

 

Hi trx680, Welcome to the Chevy Forums.

My speedometer clocks me at 120 mph while idling at a red light at times.

With corresponding oil pressure well over 80PSI. You may need a new

stepper motor for that gauge.

 

Had the same with a previous '95 Aurora, replaced the oil pressure sending unit and it worked fine.