Oil pressure in a 5.7?

rlra · April 11, 2001

I have a 1999 vortec 5700 v8 sfi engine and am trying to find the operating range for the oil pressure. I swiched over to synthetic oil and found the pressure dropped. I called the chevy service center and they gave me rough ball park answers. I really don't believe they knew what it should be. Does anybody have the factory specs? Thanks Rich.

April 11, 2001

I looked in my '95 Chilton's and it didn't specify. The general rule of thumb is a MINIMUM of 10psi of oil pressure for every 1000rpm.

So at 3000 rpm, you should see at least 30 psi of oil pressure.

Kansas Kid · April 11, 2001

In my Haynes manual it lists the minimum oil pressure as

6psi @ 1000rpm
18psi @ 2000rpm

April 11, 2001

Quote: from Kansas Kid on 6:03 pm on April 11, 2001
In my Haynes manual it lists the minimum oil pressure as

6psi @ 1000rpm

18psi @ 2000rpm

That would scare me.

Shaners · April 12, 2001

I used to own an '89 G20 conversion van. I never had alot of faith in the gauges, and my oil pressure always read low. when the motor was "hot" and at idle, it read bout ten psi. On the high way it read about 25 psi. If it was 5 degrees outside and I took off with a cold motor, it would read about 40 psi (until it warmed up).

My 5.3L carries alot more oil pressure... It is between 45-60 when warm, and I've seen 70-75 when freezing cold.

76BBSub · April 12, 2001

The Vortecs are roller cammed engines, and use high oil pressure. My 5.3 was making about 60 psi at idle. Did you switch to a comparable viscosity when you switched to synthetic? I recommend calling the synthetic oil manufacturer and telling them what you have experienced and see what they have to say. This may be pretty common, or you may have the wrong viscosity.

Jeff

CNona · December 19, 2001

My 98 5.7 Vortec runs 60-65 at cold idle and 40-45 warm on the highway.

Now, my 92 2.8L V6 reads 75 at cold startup idle, 70 at warm idle. If you touch the gas, the needle pegs (85+). It's been this way since DAY ONE when I bought it NEW from the dealer. Now, the dealership checked the gauge and didn't find anything wrong with it. They offered to switch it out for me if I wanted, but I figured "why"? What I learned is .... most of these 2.8L engines didn't last past 75k miles, some not even to 30k because of the way they oil the cam shaft - last in line. I now have over 205k miles on my little truck's original engine and I've NEVER had it opened for any reason besides a new rear intake gasket and a main seal back when it was 4 years old. It runs as good today as it ever has, strong and true. Makes me wonder if my engine has lasted this long BECAUSE I really AM getting that much pressure and my cam's getting oiled sooner (and more) than other 2.8s. I don't know for sure. Probably never will.

I'm seriously thinking of bumping the oil pressure in my Vortec so it reads 20 more psi at all times. Besides seals, what could it hurt?

chevy4x4trucks · December 19, 2001

Welcome to the forum CNona, I hope you stick around and soak up all of the usefull information here.

95Yukon · December 20, 2001

I think the 8 and 16 psi is the factory minimum recommended pressures, I do remember reading that somewhere once as well, as freaky as it sounds. Typically, it should be 10psi per 1000 rpm. I also remember reading somewhere that synthetic oils will give a lower pressure reading with the same viscosity being used, as compared to conventional oil. It flows out through all those tight clearances in the bearings easier. Check your viscosity rating. Thinner oil will show up as lower pressure on the gauge, but have a better flow rate. Thicker oil always makes the pressure increase on the gauge. If you are using a viscosity within the recommended range and the pressure was okay before that, its probably okay.

Mine reads about 60 on startup and settles in at 40 when hot (95 350) When its really hot and Im at idle it may drop to about 36-38. Those gauges aren't always very accurate, but for a before and after comparison, should be fairly close.

Its viscosity which changes the pressure reading, but you could theoretically run a low viscosity with a high flow rate oil and have better protection if its good oil. If I ran oil with the viscosity equal to 90w gear oil, my oil pressure would be 80-100psi but I would have crummy flow and engine protection. I wouldn't compare pressure to protection as long as the viscosity is right.

Just my 2 cents.

GSXER2 · December 20, 2001

As Smokey Yunick once said for every 1000 rpm 10psi is sufficient.

CMNT81 · December 20, 2001

Yea, at idle 10psi is MORE than sufficient. I think I see mid 30's at speed.

Also, our gauges aren't the most accurate in the world on top of which, two identical Vortec 5700's could come off the line right behind the other and still have calibration differences, so take what they say with a grain of salt.