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Not "normal" for a stock oil pump to create that much pressure. Either the over-pressure valve spring has been changed in a stock pump, or the pump has been replaced with a non-stock pump with different pressure schedule. For a 'race' engine, that oil pressure may be required; for a street engine it is unnecessary and wasteful on fuel.
Not "normal" for a stock oil pump to create that much pressure. Either the over-pressure valve spring has been changed in a stock pump, or the pump has been replaced with a non-stock pump with different pressure schedule. For a 'race' engine, that oil pressure may be required; for a street engine it is unnecessary and wasteful on fuel.
How does the high pressure waste fuel? Mine 78 L82 reads high after the engine rebuild but some of it may be the gauge.
I do only get 10 MPG w/ 3:55 gears.
Last edited by LenWoodruff; Sep 5, 2021 at 08:57 AM.
How does the high pressure waste fuel? Mine 78 L82 reads high after the engine rebuild but some of it may be the gauge.
I do only get 10 MPG w/ 3:55 gears.
Technically, and realistically, it takes more HP to drive the pump.
I doubt you would notice it showing up in the fuel economy at all though. There are a lot more things that take more HP than the difference between a high flow oil pump and a standard oil pump.
GM thought that oil pump 'waste' was important enough to create one that would regulate pressure to increase with RPM, so you got more lube when it is needed. For a stock, street vehicle that makes the most sense to me. Fuel saved is fuel that can take me further and keep more money in my wallet.
One thing not mentioned is whether the oil pressure gage is accurate. I don't think a single gage in my car is accurate......maybe the voltmeter. The fuel quantity is way off, the water temp is 30 degrees low, the clock.....forgettaboutit, And my oil pressure reads 80 at cruise RPM.......with 10W30 oil, stock pump, new engine. ON a real hot day, it might get down to 45 at idle. If I cared, I would try to check oil pressure with a calibrated gage, plugged somewhere into the pressure system.
One thing not mentioned is whether the oil pressure gage is accurate. I don't think a single gage in my car is accurate......maybe the voltmeter. The fuel quantity is way off, the water temp is 30 degrees low, the clock.....forgettaboutit, And my oil pressure reads 80 at cruise RPM.......with 10W30 oil, stock pump, new engine. ON a real hot day, it might get down to 45 at idle. If I cared, I would try to check oil pressure with a calibrated gage, plugged somewhere into the pressure system.
My 78 has same problems on its gauges. Temp too low, Oil to high, gas too high, clock stopped man many years ago.
Those stock gauges are not there to tell you 'exact' anything. They are there so you can recognize with something has CHANGED. Your task as a driver is to observe how the vehicle is behaving by way of your gauging. If all parameters appear as they have in the past, all is good--whether the gauges are accurate or not. If you notice that some parameter is significantly different than it has been, you need to investigate why that parameter CHANGED. It may still read an 'acceptable' value; but if it has changed, something is fundamentally different and that should be investigated.
So, the stock gauges do not need to be ACCURATE; but they do need to be REPEATABLE. And my experience says that the stock GM gauges are repeatable.
Those stock gauges are not there to tell you 'exact' anything. They are there so you can recognize with something has CHANGED. Your task as a driver is to observe how the vehicle is behaving by way of your gauging. If all parameters appear as they have in the past, all is good--whether the gauges are accurate or not. If you notice that some parameter is significantly different than it has been, you need to investigate why that parameter CHANGED. It may still read an 'acceptable' value; but if it has changed, something is fundamentally different and that should be investigated.
So, the stock gauges do not need to be ACCURATE; but they do need to be REPEATABLE. And my experience says that the stock GM gauges are repeatable.
Exactly. Once you get used to the "normal" position you "watch" closely for abnormalities.
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
10W30 - The first number in the oil rating is the cold start up viscosity. Colder climates typically require a lower number which is thinner at the low temperatures. The second number is the rating when the car is warmed up. Most car manufacturers give a range of oil viscosities based on lowest anticipated temperature that the car will see. Here is the page out of my 1968 manual.
1968 Engine Oil Recommendations
Last edited by Redvette2; Sep 7, 2021 at 04:40 PM.
