An oil thread

[DaveInDenver]

Spec for the LM/LS7 calls for conventional 5-30w, Tacometer not working but, a fair guess at 28-3000 rpm's, at/about 23-25 psi. Considering return to conventional may help? Last Oil change about 4-500 miles ago.

I meant spec for pressure but the oil weight would have some affect here. I'd expect a different pressure at the end of life of oil, probably lower since it would lose range of viscosity as it wears out and would probably be thin. But in any case new vs. old oil would vary.

FWIW, this from a Corvette forum about an LS7.

LS7 Oil pressure - what it means and why everyone's different? - CorvetteForum - Chevrolet Corvette Forum Discussion

C6 Tech/Performance - LS7 Oil pressure - what it means and why everyone's different? - I've been researchibng the forum to try to find the answer to my question: what should be the oil pressure for the LS7. Turns out, there doesn't seem to be a perfect answer and I see a wide difference from...

www.corvetteforum.com

"Owner's manual says: "Oil pressure should be 20 to 80 psi. In certain situations such as long, extended idles on hot days, it could read as low as 6 psi (40 kPa) and still be considered normal."
I recently purchased a Z06 (07' w/ 87k miles) and a friend with a similar Z06 (06', lower mileage) mentioned the oil pressure was quite lower than his in various conditions. We live in the same area, so climate is similar (Southern California).
My numbers are:
- Cold start idle: 60ish psi right at start (probably something like 70 to 80F ambiant temperature)
- Cold driving: over 70ish below 3,000 rpm
- Warm idle: settles around 20-25 psi with oil around 200F.
- Warm driving between 1.5 to 3k rpm: 30 and 50psi with the oil between 180 et 200F (I'd say if I stay at 1,500 rpm in 6th gear when it's 70F outside that 42psi would be the average observed)
The lowest pressure I saw was 17psi when idling after letting the car soak up in heat in the sun for a bit and starting up. Oil probably was around 210-220F."

 

[fyffer]

I meant spec for pressure but the oil weight would have some affect here. I'd expect a different pressure at the end of life of oil, probably lower since it would lose range of viscosity as it wears out and would probably be thin. But in any case new vs. old oil would vary.

FWIW, this from a Corvette forum about an LS7.

LS7 Oil pressure - what it means and why everyone's different? - CorvetteForum - Chevrolet Corvette Forum Discussion

C6 Tech/Performance - LS7 Oil pressure - what it means and why everyone's different? - I've been researchibng the forum to try to find the answer to my question: what should be the oil pressure for the LS7. Turns out, there doesn't seem to be a perfect answer and I see a wide difference from...

www.corvetteforum.com

"Owner's manual says: "Oil pressure should be 20 to 80 psi. In certain situations such as long, extended idles on hot days, it could read as low as 6 psi (40 kPa) and still be considered normal."
I recently purchased a Z06 (07' w/ 87k miles) and a friend with a similar Z06 (06', lower mileage) mentioned the oil pressure was quite lower than his in various conditions. We live in the same area, so climate is similar (Southern California).
My numbers are:
- Cold start idle: 60ish psi right at start (probably something like 70 to 80F ambiant temperature)
- Cold driving: over 70ish below 3,000 rpm
- Warm idle: settles around 20-25 psi with oil around 200F.
- Warm driving between 1.5 to 3k rpm: 30 and 50psi with the oil between 180 et 200F (I'd say if I stay at 1,500 rpm in 6th gear when it's 70F outside that 42psi would be the average observed)
The lowest pressure I saw was 17psi when idling after letting the car soak up in heat in the sun for a bit and starting up. Oil probably was around 210-220F."

Thanks, I did read that thread earlier, but just not used to it running that low, hence my question. But might be good then.

 

[DaveInDenver]

Thanks, I did read that thread earlier, but just not used to it running that low, hence my question. But might be good then.

It's not a yes-or-no value. You want enough pressure but not too high, especially at idle, which may indicate a problem. Pressure is force, so without pressure there would be no flow. But when you see high pressure it may mean something is preventing flow. Like when you squeeze your garden hose. In this case you're looking at the pressure difference (gradient) from high to low on a pump that's designed mainly to have sufficient flow (volume) at high RPM so that you don't starve moving parts. Oil pumps often need a pressure relief at high RPM to prevent blowing oil out of every seal. But at idle the pump is usually more than is really necessary so low pressure, as long as it's not zero, is enough. The designer tells you in the manual what's normal.