Oil pressure

I have 1992 Sierra 350 engine 5 speed,does anyone know what the oil pressure should be at operating temp.The engine has high miles but runs and sounds great ,just seems pressure running lower than usual.I have factory oil guage and it normally reads about 30 pound at operating temp. Thanks for any Help. Tom

I have a 2002 GMC Sierra and my oil pressure usually runs between 30 and 40 psi at idle. If you oil level is low, you may have low oil pressure. At one time my oil pressure was running about 20 psi. After many hours I found that the relief valve in the oil pump had partially opened and did not close back. I had to replace the oil pump and that is not a fun job.

The 92 TBI and 2002 Gen III small block (probably a LM7 but there are others) are very different.

I have owned my 90 GMC K1500 since new and now have close to 140K miles on original engine/trans. My oil pressure (with engine hot) is between 15 and 20 at idle and around 30/35 crusing at highway speeds (automatic).

My 2000 Yukon (5.3 LM7) will idle at 40 and 60 at highway speeds.

GM minimum recommended oil pressure is 6 PSI for each 1000 RPM. Personally, I would be a little nervous with 6 PSI at idle.

I think the pressure on your 92 is pretty normal for a 92 with high mileage.

//2000CAYukon

I have had a older guy 70's tell me he drains all the oil from his truck replaces it with 5 quarts of kerosene,he idles about 10 to 15 min then drains and replaces filter,claims cleans all sludge and raises oil pressure.seems a little scary to me what you guys think.

Very scary!:screwy:
I've heard of 4qts oil and 1qt kerosene for 5 minutes.
I've also heard of 4qts oil and 1qt tranny fluid for 10 minutes.
They make specific engine flush products. I would stick with those.

6 sounds about right for a production engine. Because for racing, you want 10lbs. for every 1000rpm. Plus, the higher the miles, the more wear on pressurized parts; like crank bearings become larger and wear at certain areas, this fills in oil times all the rod half shells, times the total wear on the inserts, times the wear on the crank throw becomes smaller from wear and everything rattles and looses pressure.

If you want to X-Ray your engine: Cut the oil filter open and look for bearing insert debris in brass/aluminum chips. This is a sign you need to salvage that crank journal and replace bearings with thicker meat on the bearing is to tighten the pressure up say, Band-Aid Style.