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I too have experienced the lower than traditioonal oil temps cruising for about 30 minutes in mild NC weather in my Z06. Maybe this will help add color or get rid of some internet conspiracies from forum members and Youtubers with very little subs...
I just pinged one of the GM employees that builds C8s at Bowling Green and asked for his guidance.
From what he said, there hasn't been any chatter regarding this issue at the plant, meaning it's not on their radar as a known issue. However, he did state something interesting which may help clarify the low temps.
He stated that traditionally, the oil temp sensor is on the oil sending unit by the engine block therefore reading higher numbers. The Z was engineered differently and the oil sensor is actually at the bottom of the oil tank away from the block reading cooler temps than what we traditionally used to.
He also stated that the protection or gauge will be your water temp sensors which are still at the motor level so that should be your engine temp indication. I always warm up my car to 151 degrees prior to putting it into drive and then typically stay below 4K until after 172 degrees for protection.
These factors plus the larger coolers are contributing to the lower than "normal" oil temps. Hope this helps.
On the subject of bearings; I built my first engine at 16, a big block Ford; I still remember looking at rod bearings at that age, and no one could convince me that there wasn't metal-to-metal contact. Some years later, I took a class on hydrodynamic bearing design in school and I still today find it to be a fascinating design. I'm not an expert on it, but the below is a good read on what's going on in your bearings. Some takeways are;
As previously mentioned, the engineers spend considerable time here in the design/testing phase
The LT6's 5w-50 experiences about a 2X viscosity increase going from the 220F range down to the 150F range, with temp measured inside the bearing and not elsewhere;
Bearings operate in zone 3, the hydrodynamic area, Stribeck plot, Figure 8. There is some margin allowed for RPM changes and viscosity changes. Increasing either moves you to the right, and keeps you in the hydrodynamic region. Doubling the viscosity has the same effect on hydrodynamic bearing friction as doubling the RPM.
If the LT6 entered a problem area, with too high viscosity, I'd expect to see a lowering of the redline on the tach. I don't see this at 150F, but I think in one of the videos I did see it at 116F. Don't know if this was due to water, oil, or both.
IMO - the cooler oil temps are probably OK for the bottom end ...... and follow the redline on the tach. Would be interesting to hear Tadge's take on the design considerations here.
I too have experienced the lower than traditioonal oil temps cruising for about 30 minutes in mild NC weather in my Z06. Maybe this will help add color or get rid of some internet conspiracies from forum members and Youtubers with very little subs...
I just pinged one of the GM employees that builds C8s at Bowling Green and asked for his guidance.
From what he said, there hasn't been any chatter regarding this issue at the plant, meaning it's not on their radar as a known issue. However, he did state something interesting which may help clarify the low temps.
He stated that traditionally, the oil temp sensor is on the oil sending unit by the engine block therefore reading higher numbers. The Z was engineered differently and the oil sensor is actually at the bottom of the oil tank away from the block reading cooler temps than what we traditionally used to.
He also stated that the protection or gauge will be your water temp sensors which are still at the motor level so that should be your engine temp indication. I always warm up my car to 151 degrees prior to putting it into drive and then typically stay below 4K until after 172 degrees for protection.
These factors plus the larger coolers are contributing to the lower than "normal" oil temps. Hope this helps.
Where the sensor is reading oil temps is the most plausible answer. I wouldn't be alarmed.
On the subject of bearings; I built my first engine at 16, a big block Ford; I still remember looking at rod bearings at that age, and no one could convince me that there wasn't metal-to-metal contact. Some years later, I took a class on hydrodynamic bearing design in school and I still today find it to be a fascinating design. I'm not an expert on it, but the below is a good read on what's going on in your bearings. Some takeways are;
As previously mentioned, the engineers spend considerable time here in the design/testing phase
The LT6's 5w-50 experiences about a 2X viscosity increase going from the 220F range down to the 150F range, with temp measured inside the bearing and not elsewhere;
Bearings operate in zone 3, the hydrodynamic area, Stribeck plot, Figure 8. There is some margin allowed for RPM changes and viscosity changes. Increasing either moves you to the right, and keeps you in the hydrodynamic region. Doubling the viscosity has the same effect on hydrodynamic bearing friction as doubling the RPM.
If the LT6 entered a problem area, with too high viscosity, I'd expect to see a lowering of the redline on the tach. I don't see this at 150F, but I think in one of the videos I did see it at 116F. Don't know if this was due to water, oil, or both.
IMO - the cooler oil temps are probably OK for the bottom end ...... and follow the redline on the tach. Would be interesting to hear Tadge's take on the design considerations here.
The article you linked to is a great read to understand whats going on in there. It will help everyone understand whats actually going on and why the volume of oil thru the rod bearing is primarily for cooling and how adding oil pressure and or viscosity helps band-aid an assembly that is out of its designed load range.
We ran into major issues when we brought the naturally aspirated 1.4L ZX14 engines from 175 hp to 325 hp while still using the small OEM width and diameter (1.4955") bearings. We ended up after evaluating the entire oiling system as a whole, changing almost a dozen areas of the oiling system.
The fact that its so common that stock ZX-14's destroy rod bearings when running the proper oil and level etc. tells you that they were on the edge of one or more acceptable design parameters and any added loads pushed the system into a perturbed state under high load and or added load even with Carrillo rods that stay more round than OEM rods under load. The fact that Kawasaki has had rod bearing issues sense the ZX11 and ZX12r thru ZX14 current production tells me that they feel that the failure rate on stock engines is acceptable. I'm not sure I'd agree. But then again I'm not privy to the actual warranted rod bearing failure rate numbers, I just got the many, many, calls to repair the OEM stock engines with cooked and or spun rod bearings.
I too have experienced the lower than traditioonal oil temps cruising for about 30 minutes in mild NC weather in my Z06. Maybe this will help add color or get rid of some internet conspiracies from forum members and Youtubers with very little subs...
I just pinged one of the GM employees that builds C8s at Bowling Green and asked for his guidance.
From what he said, there hasn't been any chatter regarding this issue at the plant, meaning it's not on their radar as a known issue. However, he did state something interesting which may help clarify the low temps.
He stated that traditionally, the oil temp sensor is on the oil sending unit by the engine block therefore reading higher numbers. The Z was engineered differently and the oil sensor is actually at the bottom of the oil tank away from the block reading cooler temps than what we traditionally used to.
He also stated that the protection or gauge will be your water temp sensors which are still at the motor level so that should be your engine temp indication. I always warm up my car to 151 degrees prior to putting it into drive and then typically stay below 4K until after 172 degrees for protection.
These factors plus the larger coolers are contributing to the lower than "normal" oil temps. Hope this helps.
The temp in the tank makes sense
172* coolant temp doesn’t mean the oil is up to temp
Originally Posted by RedLS6
On the subject of bearings; I built my first engine at 16, a big block Ford; I still remember looking at rod bearings at that age, and no one could convince me that there wasn't metal-to-metal contact. Some years later, I took a class on hydrodynamic bearing design in school and I still today find it to be a fascinating design. I'm not an expert on it, but the below is a good read on what's going on in your bearings. Some takeways are;
As previously mentioned, the engineers spend considerable time here in the design/testing phase
The LT6's 5w-50 experiences about a 2X viscosity increase going from the 220F range down to the 150F range, with temp measured inside the bearing and not elsewhere;
Bearings operate in zone 3, the hydrodynamic area, Stribeck plot, Figure 8. There is some margin allowed for RPM changes and viscosity changes. Increasing either moves you to the right, and keeps you in the hydrodynamic region. Doubling the viscosity has the same effect on hydrodynamic bearing friction as doubling the RPM.
If the LT6 entered a problem area, with too high viscosity, I'd expect to see a lowering of the redline on the tach. I don't see this at 150F, but I think in one of the videos I did see it at 116F. Don't know if this was due to water, oil, or both.
IMO - the cooler oil temps are probably OK for the bottom end ...... and follow the redline on the tach. Would be interesting to hear Tadge's take on the design considerations here.
The lowered redline is because it wasn’t at 500 miles yet, is it lowered for oil temp? Also what is the thermostat temp of the C8 as 170s seems low for coolant with today’s emissions no?
172* coolant temp doesn’t mean the oil is up to temp
The lowered redline is because it wasn’t at 500 miles yet, is it lowered for oil temp? Also what is the thermostat temp of the C8 as 170s seems low for coolant with today’s emissions no?
My C8runs cooler than my C6 did until I went to a 172* T-stat. My C8 frequently runs below 180* on highway runs in cool weather.
Regarding the tach, the redline starts around 5000 rpm when started cold; depending upon the ambient temp. I tracked oil temp vs redline when I first got the car (post-500 miles). It gradually moves to 6500 rpm as the car warms up. Full redline occurs around 150* - 155* of oil temp.
My C8runs cooler than my C6 did until I went to a 172* T-stat. My C8 frequently runs below 180* on highway runs in cool weather.
Regarding the tach, the redline starts around 5000 rpm when started cold; depending upon the ambient temp. I tracked oil temp vs redline when I first got the car (post-500 miles). It gradually moves to 6500 rpm as the car warms up. Full redline occurs around 150* - 155* of oil temp.
Yeah my C6GS sits runs around 190* on coolant and oil is usually 100* above ambient. The C8 running cooler on water temp makes sense it then runs cooler on oil though it does have a smaller oil capacity. I run 0W40 in my LS3 like the LT2, but LT6 runs slightly thicker 5W50. 5k vs 6500 doesn’t seem like much of a limitation, what does the C8 oil temp run cruising in cold weather? Have not heard of any C8s having cooling issues at the tracks here in Texas though.
Doing some searching I came up with 3500rpm soft limiter/hard limiter 4500rpm until 135* oil temp, but sounds like it was variable and maybe 5k rpm was allowed at 150*? Other posts say it’s not actually a hard lower limiter and just a suggestion, the C8s I’ve driven were not handed over cold so I’ve never experienced this personally.
Audi RS5 limits to 6k until 140* oil temps and then you get the full 8k rpm, that ran a 5W40. BMW waited till 150*, but they ran a thicker 10W60 for their 8k rpm V8. I’ve personally always waited to go above 2k rpm till 130* oil, here’s the GT3 for reference.
Doing some searching I came up with 3500rpm soft limiter/hard limiter 4500rpm until 135* oil temp, but sounds like it was variable and maybe 5k rpm was allowed at 150*? Other posts say it’s not actually a hard lower limiter and just a suggestion, the C8s I’ve driven were not handed over cold so I’ve never experienced this personally.
Had been traveling, so haven't driven my C8 in a while. Fired it up and redline was at 4500 rpm on the tach. I believe it is a suggestion and not an actual rev limiter, although I've never tested it.
Put a 100 miles on my Z06 today on backroads. Air temps mainly in the low 40s. Oil temp never went above 155*. Hitting 150* only happened once in some slow stop and go traffic. 40 MPH seems to be the magic speed for airflow. Anytime I was at 40 MPH for a mile or more temps started to drop until the mid 130s. Typically around 136 - 138*, although I did see it drop to 133* This picture is after about 35 miles of driving:
The LT2 provides full redline once the temp crosses 130:
Put a 100 miles on my Z06 today on backroads. Air temps mainly in the low 40s. Oil temp never went above 155*. Hitting 150* only happened once in some slow stop and go traffic. 40 MPH seems to be the magic speed for airflow. Anytime I was at 40 MPH for a mile or more temps started to drop until the mid 130s. Typically around 136 - 138*, although I did see it drop to 133* This picture is after about 35 miles of driving:
The LT2 provides full redline once the temp crosses 130:
Thanks for sharing and congrats! 130* and above has always been my cut off for letting it rip. At ambient temps that cold any performance tire is going to have an issue with grip, so unless one has swapped to all seasons and out canyon carving in freezing temps I don’t see a concern.
One thing that's interesting is how GM is OK putting pretty different oils in cars for track use. Even the 2023 C8 track prep guide shows 0w40 for LT2 and then says you can run 15w50 on track. Even though it's the Stingray and Z06 guide the oil section doesn't mention the 5W50 at all. It's being mentioned folks I trust online that you can run 5W50 in the LT2 all the time as well and it will offer more on-track protection than the 0w40. I just had my oil changed, but next change I'll probably move to the 5W50 and just leave it.
Will the "folks I trust" pay for a non-warranty repair if necessary? GM says you can use 15W-50 on the track in the LT2, but says you need to drain it and replace it with 0W-40 after the track session. That tells me they don't want 50 weight in there for street use. Like any other "modification" of the factory design, you accept the risk if something goes wrong.
Will the "folks I trust" pay for a non-warranty repair if necessary? GM says you can use 15W-50 on the track in the LT2, but says you need to drain it and replace it with 0W-40 after the track session. That tells me they don't want 50 weight in there for street use. Like any other "modification" of the factory design, you accept the risk if something goes wrong.
Yes… sales manager at one of the largest Corvette dealers. You’ve got it backward. They don’t want 15 in there for cold starts.
and in a cold climate where the oil is going to be thicker, most engines have a recommended weight of oil based on temperature.
"Most" is a false claim for modern vehicles & engines. Most manufacturers now recommend a single weight across an engines usable temp range. Technology has come a long ways; good thing lubricant engineers and GM engineers have done enough validation testing to warrant the engines for longer than most original owners will ever see.
Things like this are exactly why a lot of vehicles don't include any actual accurate temp gauges; it just raises needless questions from paranoid and/or uninformed customers.
Neither sales managers nor dealers make warranty decisions on an engine problem. GM does. And GM won't care what the sales manager told you. LOL.
I’ve owned many cars, built many racecars, built engines as well I know how this all works. You’ll soon be seeing 5w50 is approved for LT2 full time use.
I’m not posting the name as it was a private conversation, but this person is well entrenched with GM engineers in Michigan.
"Most" is a false claim for modern vehicles & engines. Most manufacturers now recommend a single weight across an engines usable temp range. Technology has come a long ways; good thing lubricant engineers and GM engineers have done enough validation testing to warrant the engines for longer than most original owners will ever see.
Things like this are exactly why a lot of vehicles don't include any actual accurate temp gauges; it just raises needless questions from paranoid and/or uninformed customers.
So you’d run the same oil in the winter if you lived in Minnesota as in the summer if you lived Texas?
