Hello, I noticed this tonight and i genuinely need help as I have no idea what this could be? Ever since ive owned my camaro (1995 3.4l) oil pressure has always been around 40 at startup and 15 to 30 at operating temperature, during the winter oil pressure was always a problem as it would be extremely low (around 10 if i could estimate) so during the winter i would put a higher viscosity oil in the engine, but even one winter after putting in 10 w 50 in the pressures would rarely pass 40. today i was driving home from work and I hit a bump (this is when I noticed because my car has so many problems when i hit large bumps i tend to look at the gauges) i noticed oil pressure was now at around 75 (cold start its about 60 outside and the engine currently has mostly 5w20 in it and a tiny bit of 10 w 50 because i ran low and it was an emergency) when it hit operating temperature it would idle at 20 to 25 now and when i accelerate it climbs at a steady pace to the notch that represents 60... I what does this mean?? what are the "Normal" oil pressures for cold start and operating temperature on this engine? and could this imply i have a blocked oil passage? if so I assumed it would be high constantly? also as a side note this car has had many oil leaks and im down to one left on the engine and before tonight whenever it was up to temp and i turned on the Heat or was idling long enough i could smell burning oil (from it running down the block onto the exhaust pipes) but tonight no smells? all replies are appreciated as ive kept this car alive way too long and am going to continue to fight to keep my POS running haha

 

Also! since ive gotten the car ive replaced the oil pan and rebuilt the top half of the engine so i know there isnt any debris in the oil pan or upper areas of the engine (including the visible ports on the block as far down as you can reasonably see into those tiny holes) It still has an oil leak because I was young and didnt care about torque specs lol but ive replaced and fixed every part and leak besides tightening the heads which is where i suspected the leak is coming from. Just some after info incase the conclusion is that an oil passage is blocked, the engine was running normal temperatures and it has no debris in it as far as i rebuilt and cleaned.

 

Oil pressure can be an indication of engine wear. As bearing wear clearances in the engine get bigger the engine requires more oil volume. It can also be an indication of wear on the oil pump itself. BUT factory gauges are unreliable. You need a real measurement of oil pressure with a good hand held gauge. The fact your oil pressure "changes" on bumps is even more of an indicator the this is a gauge issue. An engine that at of near zero oil pressure will make a lot of noise, mostly valve clatter at first. As a rule of thumb you 10 PSI per 1000 RPMs to not damage a motor.

FYI even at the dealership about 95%+ of the complaints of low oil pressure turn out to be a gauge issue so unless you car has really high miles I doubt it is super low oil pressure with 20w-50 in the car. There are a few things that can cause an "all of a sudden" oil pressure issue. Oil pump damage, antifreeze in the oil and over heating.

 

Do you have a recommendation for a handheld oil pressure gauge? ill look into them and yes it has about 170k miles so i figured it isnt like anything very serious because no new smells, no over heating or anything like that. and okay i called my old coworker who's much more knowledgeable in every area than me and he said thats the normal operating area typically and its probably just the gauge has been old and crappy basically

 

You can buy a cheap gage if you have a compressor with a gage and a regulator. You can prove the gage before using by making sure it matches the air pressure gage. If you do not it may be cheaper to just have a garage do it. A decent gage will cost you 80 ish bucks.

 

Find your oil pressure switch, unplug it, and see if there is any oil on/in the plug. If so, the switch is bad. It could be bad even if it isn't leaking, which is where I would start based on your description. Your lower oil pressure in the winter is the opposite of what should happen, leaning toward it's less likely being a mechanical (worn bearings) issue.

 

Good luck finding an oil pressure transmitter that reads correctly. i have tried numerous brands from various parts box stores on my 94 model 3.4, and none read the correct pressure. i have tried dealer and they didn't sell them any more (a few years back). i have a bosch in now an it reads high like yours.

 

Rockauto.com carries an ACDELCO oil pressure switch. I would not use the box store brands.