Low oil pressure

I have 1998 GMC Savana, 5.7 ltr, with 132,000 miles. Recently the oil pressure has dropped. At idle its near zero. The engine interior is very very clean. Ive changed the oil sending unit, added a mechanical gauge and now have changed the oil pump. Same results. Its not making any bad noises,yet. Any ideas?

Have you done a compression test?

Oil pressure at idle can be low and it won’t hurt anything, If it goes up to a normal at cruising I wouldn’t worry. On some of the rice burners 3-5 at idle is OK. Some of owners manuals reccomend 5W-30 and they so that to increase milage. Your next oil change I would change to a slighly heavier oil and see if that get you a couple more PSI . That many miles on American engine started to take its toll!! MHO

Not good!

New oil pump? Mechanical gauge? And the oil pressure is still low?

The lower end of the engine is worn out.


I am not sure I would condem the motor just yet. Where are you taking your oil pressure reading from?

If you’re taking the oil pressure reading off of the sending unit port then I agree you have an internal problem in the engine; worn crank journals and bearings, etc.; noise or no noise.

The mileage is pretty low for something like this on one of these engines, but it also depends on oil change frequency, if you’re the original owner, if it has ever been run out of oil, etc.

A compression test for low oil pressure???



All engine builders quote 10 PSI per 1000 RPM as a the minimum for a small block chevy 350 (what you have in your van.)

If this recently happened, was it in coincidence with an oil change? If so, did you change the filter? Was the proper filter installed? If Yes, and Yes, you may suspect the filter’s valving or construction.

What is the PSI rating at various RPM sample ranges? Does it get up to 30-40 PSI at “highway speeds?” If so, no worries, drive it. But suspect that this engine is reaching its end of life.