Corvette1221

Ok, I have been spending alot of time watching my oil pressure, since I have now heard of two people that have spun bearings do to low oil pressure. One guy posted some pictures of it, man those bearings looked bad.

So I am driving home on the freeway here in California. It is a cold night and I am cruising just around 75mph. The speed limit is 70. The temperature, according to the car is 61 degrees f. Water temp about 195f. I had been driving like this for about 25 minutes before I hit some traffic.

I look at my oil pressure and it is about 60psi, oil temp 157f. Rpm about 1700 in sixth gear.

Ok, then I hit a traffic jam. Waiting in traffic I notice that when I am idling my oil pressure drops to 31psi at about 600rpm. Wow!! That's low I thought? I check the gauges and I find out that my oil temp is 194f, water temp 216.

When I was in the traffic, for about 3 miles at 7mph, a good 20minutes time or so, the oil pressure continued to do this. The minute I hit the accellerator it would quickly jump back up to about 48psi at 1200rpm.

But if I let off the gas it would drop back down to almost 30psi. Here is the kicker, the minute I got off the freeway where I got the car back up to about 70mph, the oil cooled down to 184, water temp 190f, the oil pressure was now 48psi at 600rpm???

What is the deal?? Now I know that when oil is cold it is thinner so it will provide more pressure. If you don't believe me on this, just look at your oil pressure when you start a cold engine. You may have 50 to 70 psi when it is cold at idle.

However, why would the difference between 196f down to 184f make a difference of almost 20psi during idle?

Is something going on here that shouldn't be happening? Are these signs of a failure that might happen? Most of the time my oil temp doesn't get that hot unless I am pushing the car. But if I am pushing it then my rpms are high so I have no problem with oil pressure.

But what if I was stuck in traffic on a hot day?? Would it be worse? Since I usually avoid traffic with the car I don't notice low oil pressure, but this time it made me worry just a little. I wonder what the regular oil pressure should be, what is the lowest it can go and still provide lubrication?

If I am just driving around, unless it is a hot day, most of the time the oil temp never gets above 184 so I don't see it drop below 40psi.

Can anyone tell me if 31psi is too low at idle? What would cause these strange occurances? I have noticed that it takes very little rpms, only about 1200, to get the oil pressure back up to 50psi. But I am worried about the idle pressure at 600rpm.

Anyone else experience this??

Icebourg

hawaiianswiss

Sound normal to me!
Mine also sometimes drops to 28-30 Psi at idle. Once I give it some gas it goes back up!

As long as it doesn`t drop under 20 Psi you should not worry!

Av8terZ06

Your oil pressure sounds completely normal. A good rule of thumb is 10 psi for every 1000 rpm. You wont be able to monitor the oil pressure in the way that you are thinking in order to prevent a bearing from spinning. If you do spin a bearing, you will hear a loud knocking and eventually the motor will sieze. If it happens, there is nothing you can do to prevent it and the motor will have to come out. Also if it happens, it will probably be due to a dirty engine assembly, faulty or design flawed parts, incorrect tolerances, etc. Very low oil pressure could indicate worn or bad oil pump, bearings, or loose tolerances etc. So other than your oil pressure dropping to zero or close to it, at which point im sure you will get an indication of that, everything sounds fine. As for what is causing these occurances, you have to take everything into account. First you stated its a cold night, the vette has a massive 8 qt oil tank external of the engine which will somewhat cool the oil unlike a conventional engine where the oil stays inside the oil pan, and your rpms are relatively low during cruise and idle so youre not flowing all that much oil. So by the time the oil leaves the engine, sits and cools in the sump, and finally re-enters the engine, the temp of the oil is going to slightly change which is going to slightly change oil pressure. Anyway, i wouldnt worry about anything and it sounds normal.

outnumbered

It sounds normal to me. The lowest I have seen was 18 at idle after a hard session at an HPDE. The oil was 260's.

A cool down lap is really important on the track. One lap cools everything down by a large amount. Same at home. If you do some spirited driving and return home, cruise around normally for a bit to cool things closer to normal before you park.

Corvette1221

Thanks for all the advice guys.. Forum members on here are great