Question: 1984 standard vs. high volume oil pump install w/standard oil pan

[Hib Halverson]

As for the issue with the EOC on the 91...is this car a Z51 with the stock, HD engine oil heat exchanger?

Also, I'm unclear as to the specifics of the oil pressure problem. What's posted implies that oil pressure is ok until the engine goes wide-open-throttle. Does that happen at any RPM?

 

[John Robinson]

[QUOTE

Mobil 1 15W50 oil with Delco stock filter.[/QUOTE

]

OK it is my understanding that the 15 relates to the thickness of the oil at start up and the 50 is the thickness at full temp. So if that is the case then (for the sake of illustration) a 5 w oil cold would have the consistency of water and a 15w oil would be more like chocolate syrup. Following that up to the 50W oil your using hot it would become something like a thick shake. Now think about when you have a think shake you can draw some of it through a straw if you don't try to suck on it to hard(Like running along at a normal throttle). However if you give a really good hard pull on the straw(WOT) you find you are really straining and the shake is not coming out very fast. What you may have is a case of the oil being too high in viscosity to flow through the oil passages freely. If that is the case I would guess that when you go WOT the engine temperature rises.

In the days gone by when we only had a single weight oils we used high weight oil . The tolerances in the engines 40 years ago were not what they are today. That's why we expect to get 150K or more from our cars engine but in the past somewhere over 30K you started to lap the valve and at 50K it was a complete rebuild.

 

[John Mekisich]

Oil Preference

Hib, Prior to switching to Amsoil I used Red Line for many years with no issues. I changed as I have a Amsoil dealer with a walk in retail store very close to where I live. In another post you said that you would not consider using Amsoil oil or filters. May I ask why?
I respect your opinion and would be interested in what you have to say. From research I have done, their filters seem to offer excellent performance and durability and my impression was that Amsoil and Red Line synthetic oil were equivalent products.

I use Red Line synthetic 10W30 in all my engines except for the Big-Block in my 71 in which I use Red Line 10W40. To mitigate the cost a bit, I use extended drain intervals on all engines but I change filters every 3000-5000 miles. On engines in cars that see more than 10,000 annually, I change oil at 18,000-22,000 miles. On the others, I change the oil about every 24 months. I use the Analysts Inc. as my spectrographic oil analysis lab and for over a decade my oil change intervals and filter change intervals have worked quite well.

As for filters, what I use on most of my engines is no longer available. For a short period in the early 00s, ACDelco had an ultra-premium filter line called "Ultraguard Gold" which were made for ACD by Champion Filter (not to be confused with Champion Spark Plug). I bought a large quantity of the PNs I use which are UPF44, UPF52 and UPF1218. I'm still using that supply. On my LT5, because ACD never made a UPF filter for that engine, I use the Mobil 1 M1-207

If I had to buy oil filters now, I'd probably buy WIX oil filters or the standard AC oil filters except for the LT5 where I'd still use the Mobil 1 filter.

 

[boomdriver]

[QUOTE

Mobil 1 15W50 oil with Delco stock filter.[/QUOTE

]

OK it is my understanding that the 15 relates to the thickness of the oil at start up and the 50 is the thickness at full temp. So if that is the case then (for the sake of illustration) a 5 w oil cold would have the consistency of water and a 15w oil would be more like chocolate syrup. Following that up to the 50W oil your using hot it would become something like a thick shake. Now think about when you have a think shake you can draw some of it through a straw if you don't try to suck on it to hard(Like running along at a normal throttle). However if you give a really good hard pull on the straw(WOT) you find you are really straining and the shake is not coming out very fast. What you may have is a case of the oil being too high in viscosity to flow through the oil passages freely. If that is the case I would guess that when you go WOT the engine temperature rises.

In the days gone by when we only had a single weight oils we used high weight oil . The tolerances in the engines 40 years ago were not what they are today. That's why we expect to get 150K or more from our cars engine but in the past somewhere over 30K you started to lap the valve and at 50K it was a complete rebuild.

Because oil is pushed by a gear pump that does not care how thick or hot/cold it is, the viscositys job is being heavy enough to stay inside loose bearings and prevent shearing (contact under pressure between the parts). The hotter it gets the worse that becomes, so oil has to be thicker in order to compensate.

Thick oil is more difficult to push, so HP is absorbed and lost before it even gets measured at the crankshaft. Thats where thin, easy oil becomes important. We want oil thick enough to protect against shearing, but thin enough to be easy to push. I read once that in theory, the avg V8 engine can waste as much as 20 HP internally:ugh either from splashing in oil, (counter-weights use approx 9hp as they splash in a pool of oil) pushing the oil and the weight & resistance of the parts of the oil pump drive system. Thats amazing.......Thats why we like 0-10wt or 5-20wt oils in new engines with their super tight tolerances. In 1965 a 0-10wt motor oil was "break-in" oil to be disposed of after 500 miles then 30wt or 10-40wt was installed for normal use.

Engineers have been forced to look at every aspect of where HP goes and why 300hp generated is only 237 usable on the ground.
They have to when it comes to producing clean running, hi-performance engines that the public will actually buy, regardless of what the EPA guidelines are. If they can free that lost 63 hp to be used at the wheels, they've earned their pay for the week.

Hot oil is less capable of lubricating because it thins out. Polymers are added to make oil thicker when hot and stay thin when cold.

As metals expand, holes get bigger,loads rise, shearing increases. Being able to make oil get thicker when hot yet stay thin enough to circulate easily when cold was the biggest advance in petroleum/automotive engineering since the grease gun.

 

[aklim]

As for the issue with the EOC on the 91...is this car a Z51 with the stock, HD engine oil heat exchanger?

Also, I'm unclear as to the specifics of the oil pressure problem. What's posted implies that oil pressure is ok until the engine goes wide-open-throttle. Does that happen at any RPM?

Yes it is a 91 but not a Z51. It came with the KC4 - Engine oil cooler option

No it does not happen at any rpm. Within limits, the oil pressure goes up as rpm goes up. When you go WOT it goes up for a couple seconds then drops down to about 20-25psi. Other RPM is fine.. Pressure is over 40

 

[Hib Halverson]

Yes it is a 91 but not a Z51. It came with the KC4 - Engine oil cooler option

No it does not happen at any rpm. Within limits, the oil pressure goes up as rpm goes up. When you go WOT it goes up for a couple seconds then drops down to about 20-25psi. Other RPM is fine.. Pressure is over 40

I won't argue with you about the indicated oil pressure's behavior being odd.

First thing to do is confirm what you see on the car's oil pressure display using a known good, perferably mechanical, gauge. Post the results when you have them.

 

[Hib Halverson]

Hib, Prior to switching to Amsoil I used Red Line for many years with no issues. I changed as I have a Amsoil dealer with a walk in retail store very close to where I live. In another post you said that you would not consider using Amsoil oil or filters. May I ask why?
I respect your opinion and would be interested in what you have to say. From research I have done, their filters seem to offer excellent performance and durability and my impression was that Amsoil and Red Line synthetic oil were equivalent products.

I've used Red Line Synthetic Oil in my engines since about 1989. I've also used Red Line's transmission and rear axle lubricants since 1990. I've used Red Line Water Wetter since the consumer version of the product went on sale in the early 90s. Red Line Engine Oil has performed very well for me. Amsoil has never presented a technical or cost case to me that's attractive enough to change. I believe the performance of both products while incrementally different, will be, in a practical sense, similar if like products are being compared.

I've never been a supporter of products which are multi-level marketed.

I know that Red Line supports the Corvette hobby more actively than does Amsoil.

As for Amsoil-branded oil filters...I've never used that product. I have never examined any filter comparison test data about it. I do not know who makes Amsoil's filter so I can't comment.

 

[boomdriver]

Yes it is a 91 but not a Z51. It came with the KC4 - Engine oil cooler option

No it does not happen at any rpm. Within limits, the oil pressure goes up as rpm goes up. When you go WOT it goes up for a couple seconds then drops down to about 20-25psi. Other RPM is fine.. Pressure is over 40

I'll 2nd what Mr. Halverson says,

Get a known to be good, mechanical gauge installed and observe it thru all the usual driving conditions and make notes. Duct tape on the windshield time...
Use lots of tape so the gauge is steady and does not vibrate...otfl Nobodys gonna stare...

At this point, if I had to venture a guess, it would be electrical, in the harness to the gauges or the sender.

Hydraulics are governed by the laws of the physical universe, so, unless there is a way that the pressure & volume is being relieved ONLY when WOT is applied, OR the system is not responding to the sudden increase in torque on the pump shaft, then the reading has to be false.

Is it possible for the oil pump drive shaft to be stripped and allowing the pump to slip on the shaft when the sudden surge in torque is applied??????????:confused

 

[Corvette95]

normal oil pressures in 94 LT1 according to Alldata....

I know this is an old thread but my oil pressure keep reading low, I replaced the pump with stock pump this past weekend with same pressure reading. My alldata subscriptions says pressures are: Normal Oil Pressure psi Engine hot, minimum oil pressure @ 1000 RPM, 6 psi.; @ 2000 RPM, 18 psi.; @ 4000 RPM, 24 psi.this seems low to me. I havent done a pressure reading other than the gauges, what is the correct gm pressures?

 

[strokin383-c4]

my 2 cents.

I deleted my spare tire bracket and holding unit in the rear and installed an oil sump, I ran the lines along side the exhaust so the oil stays warm, my oil pressure is always around 60-65 at cruising RPM's and my oil is always around 200-215 F. The sump system was around $400 and I did the install myself. Also the sump is much better for auto-crossing due to a direct oil injection so you dont deal with "splashing" in the pan. your engine is always receiving the same amount of oil distribution.

 

[strokin383-c4]

I know this is an old thread but my oil pressure keep reading low, I replaced the pump with stock pump this past weekend with same pressure reading. My alldata subscriptions says pressures are: Normal Oil Pressure psi Engine hot, minimum oil pressure @ 1000 RPM, 6 psi.; @ 2000 RPM, 18 psi.; @ 4000 RPM, 24 psi.this seems low to me. I havent done a pressure reading other than the gauges, what is the correct gm pressures?

2000 oil pressure should stick around 40-50 PSI. on a stock L98 or LT series. you can check by turning your key to the "accessory" position and making sure your gauge reads "0" if not, your sending unit is off or your gauge needs re-calibrated.

 

[boomdriver]

I know this is an old thread but my oil pressure keep reading low, I replaced the pump with stock pump this past weekend with same pressure reading. My alldata subscriptions says pressures are: Normal Oil Pressure psi Engine hot, minimum oil pressure @ 1000 RPM, 6 psi.; @ 2000 RPM, 18 psi.; @ 4000 RPM, 24 psi.this seems low to me. I havent done a pressure reading other than the gauges, what is the correct gm pressures?

You're answering your own question....

Those are GM minimums...the least amount of oil pressure that you should have. Any less is not acceptable, any more is OK.

Double those numbers for a hot engine to fall in the middle of "normal" and not new. Twice those minimums is about where my engine runs, but I am also closer to 200K on this motor.

It still idles hot at 15-20 and jumps to 50 psi instantly when rpm increase. I used to worry that 20 was low for a hot idle, but when it was brand new was the ONLY time it showed more pressure.