Hey Guys,
I have a 1992 GTA with the 350 L98 motor in it and 45,000miles on it, bone stock. I bought the car a few months ago so I'm still pretty new to the F-body world, and have a question about what's the proper oil pressure for the car. When I start her up cold, the oil pressure's somewhere around 45-50psi and after it's warmed up it drops to about 30psi (middle of gage). If I rev the motor the oil pressure goes up, or if I'm accelerating the pressure goes up as well (depending on hard how I press it down I know all of this is normal.
But.... after fully warmed up if I let the car idle for a while (either in traffic or just sitting) the oil pressure goes down to as low as 15-17psi. Is this good or bad? To note the motor sounds perfect, even at 15psi, like I said before only 45k miles on it, but I don't want to take any chances with it. So is this bad? Or am I just worrying over nothing? Or possibly could the oil pressure gage or sensor not be working 100% accurately?
Thanks for your help!
~Keith

 

naw, its not bad, more than likely its just your guage, very very common with the 3rd gen,

 

also in traffic the engine temp is getting warmer and the oil pressure drops even more.. i think your engine sounds fine.

 

would a new sending unit make it read differently?

 

10 psi per 1000 rpm is acceptable oil preasure

 

Hey Guys thanks for the replies!! Now I won't be soo nervous when I'm out crusin' thanks!

 

I'm gonna bring this back from the dead because I've been wondering about this recently. My 1992 B4C Camaro with the L98 has around 104K miles on the L98. My experiences are very similar to the original post, pressure seems fine when the car is cold, maintains 45-50psi in all situations. But when it warms up the pressure drops to somewhere between 15-30 psi when below 1000 RPM (which is basically at idle or slowing down). Above 1000 RPM is will maintain 45-50psi, even when warm. My car dosnt run extremely hot or anything I'm talking between 180-200 degrees in all situations (even stop and go traffic). I'm thinking it might be the oil I'm using and how its reacting to the heat. I can't say how accurate the guage itself is, but the guage is consistent and it does not bounce at all. I've read here that 10psi should be acceptable below 1000 RPM, but I'm interested in what I can do to make this more than just acceptable, I want it to be optimal so the engine lasts as long as possible. Would running a different weight oil or an additive help me out here? I use Mobil 1 synthetic 10w30, been thinking about adding an oil stabalizer but I dunno. I just dont like the idea of the oil pressure getting so close to the red area when the car is warmed up and under 1000 RPM. Should I be worried? My friend's L98 engine in his 91 Z28 blew while cruzing down hill off throttle at low RPM's, got me thinking about what my cars are up to at low RPM's. If anyone can chip in I'd appreciate it. I want this B4C to run perfect forever hehe.

 

CrazyHawaiian - I was a bit shocked to see my old post is back again from March '03. Brings back memories when I first bought my 'bird. I still have her now and she still runs perfect (just broke 51k miles last weekend <--can you tell its not a daily driver? )

Anyway, as I made the original post I'm obviously NOT the expert on the matter LOL but I will tell you this. I use Mobil1 5w-30 and to this day I still maintain the same oil pressure as in my original post. I did once put 10w-30 in it, and the car had much more oil pressure. Basically at idle I was making 25-30psi, and under normal acceleration/highway cruising the gage was just about pinned.

So, in my opinion different weight oil / additives WILL make a difference. But lets see what the experts say. Anyone care to add??

 

crazy hawaiian, at no load under 1000 rpms 10 psi is more than enough for a motor. I would not change your oil as you're using one of the best oils for that motor already. mobil 1 is definately the way to go. I wouldn't worry about it one bit. I had an old chevy that would drop to 12 psi at idle and 30psi at 3500 rpm, it was in a old truck of mine, took 347,000 miles to finally give up the ghost and i beat on that truck all the time and towed loads with it and it was fine.

 

any service manual I've ever seen for a SBC list the minimum oil pressure at 7() PSI@1krpm and 18 () at 2krpm, personnally I think that is incredibly low. I'm not particularly happy w/ my engine's 15 PSI @ it's 450rpm idle, but I've got decent OP at 1k and above.

 

Glad I saw this post as I was going to post another one on this very subject. Here is my deal. Bought another L98 '88 GTA last week. Been driving it around a few days and the oil pressure is weird.. It will start and idle at about 45 psi and run at around 50 psi. When it gets warm it idles around 30psi and cruises at about 45 at 2K rpm at 220* or so. About 20 minutes into driving at highway speed it will start to dropoff between 12 psi at idle and 20 at cruise and it will drop all the way to the gauge sitting right above the red line at idle in gear and it will do this for a while. Then I'll drive the car around and then it gets pressure from 12 psi to maybe 20 psi at cruise speed and it will stay like this until i park it and it gets cold again and I start it up and the whole scenario starts over again. I changed the oil with Havoline 10w-40. Thinking Im gonna change it again with 20-50 to see what happens. Is it truly an oiling problem or is the gauge just messed up? Keep in mind that when the pressure gets down to touching the red the motor sounds fine the entire time. Dosen't click, no valve noise, no power loss, nothing. Everything seems totally normal besides the oil gauge.

 

It does sound like oil or bearing clearance related issue. For 1/4 the price of changing the oil you can go buy a mechanical gauge and then you will know 100% if its the gauge acting up or not!

 

I hooked a mechanical gauge up to it and it idled around 10 psi and at rpm it got around 45 but this was just with it idleing in my driveway at temp. I mean, I've really got on it a few times and it never did anything strange. Other than it reading weird the motor seems fine. I dunno...

 

replace the oil pressure sender GTAjoe....i've done this to several vehicles, they either fail to zero or they fail to above the 80 line. It's like a heat soak in the sending unit causes them to read wrong. Buy a new one and swap it out and it should fix itself.

 

I tried a new one. Same thing.. Its weird. I would think that if it were an actual internal engine problem that it would be like that all the time, like you would either have solid pressure all the time if there wasn't an issue or if there was something wrong with the motor it would drop pressure as soon as the oil got warm and it being great, and then nothing, and then mediocre pressure. Dosen't make sense..