GM recommends Mobil 1 15w50 for 2016 Corvette

[ZeeOSix]

Originally Posted By: SR5

Anyway, this is an interesting and lively discussion on heat source and flow in a high performance engine. If it can be kept friendly, there is a lot of good stuff here, from many different angles. I for one had no idea that RPM builds oil thickness until Shannow posted that graph a few pages back. It makes sense to me, and it supports my view that my old low revving thumper motorcycles needed thicker oil (that and being air-cooled). But I now realized I transferred this world view to my high revving 4-cylinder motorcycles without realizing that it wasn't quite the same, and maybe my oil was a little too thick for that application. No harm done to the bike, but it's nice to learn new things, even if it's a little challenging.


Thicker oil also builds more oil film thickness on top of the RPM, so if you were using a "little too thick oil" on your newer high revving bikes I doubt it was too thick and actually gave you some added MOFT protection. Most modern high performance bikes that rev to 11~12K RPM still specify a 10W-40, and all will have a dedicated oil cooler. My 2016 Yamaha XSR900 redlines at 11,200 RPM and Yamaha specifies 10W-40, but also shows you could run as thick as 20W-50 if ambient temperatures aren't too cold (above 50F).

 

[SR5]

Originally Posted By: Nickdfresh
Originally Posted By: SR5
Originally Posted By: Nickdfresh
Originally Posted By: Shannow

Charts in question were taken from a paper on warm-up strategies...i.e. intentionally getting heat into the oil, and comparing which strategy (RPM or load was more effective).


Right, bud. Where's the link?

Whose paper? Was it peer reviewed?

As opposed to your pseudoscience posts that have caused a number of posters to quit this place...


Come on, that's not fair, Shannow does some of the best science and engineering posts here. None that I have seen deserve the title pseudoscience. The quality of his posts has kept me coming back to this place.

I can't speak for Shannow, but I grab lots of graphs and tables from the web, like J300 tables, that I then refer to. Unfortunately I can't always point to the source, as it wasn't important at the time (and I was being a bit lazy). However if somebody says my J300 table is out of date, and provides (or points to) a better one, then I'm happy to be corrected.

Anyway, this is an interesting and lively discussion on heat source and flow in a high performance engine. If it can be kept friendly, there is a lot of good stuff here, from many different angles. I for one had no idea that RPM builds oil thickness until Shannow posted that graph a few pages back. It makes sense to me, and it supports my view that my old low revving thumper motorcycles needed thicker oil (that and being air-cooled). But I now realized I transferred this world view to my high revving 4-cylinder motorcycles without realizing that it wasn't quite the same, and maybe my oil was a little too thick for that application. No harm done to the bike, but it's nice to learn new things, even if it's a little challenging.



Maybe I was a bit strong on the psuedoscience thing, but I think there is also a danger in posting dated research as gospel or the end all be all...


Yes I certainly agree that dated or one-off research is a concern. It's a problem through all of science and engineering, you can get funding to measure something new (sometimes) but nobody will fund you to reproduce a 20 year old measurement just to check if it still holds.

Now add a pinch of graphene to the oil, the "it" material of today, and you will probably do OK funding wise.

 

[SR5]

Hi ZeeOSix,

Thanks for that chart. Yes, I just had a bigger MOFT reserve, but no harm done. Off the top of my head I went from a red-line of about 4000 RPM to about 12000 RPM. Running Penrite 20W-60 mineral or Castrol 10W-60 synthetic in both. I probably should have dropped it to 10W-40 syn or 15W-40 HDEO in the four cylinder bike. The HDEO would have saved me a few dollars too.

I'm now using things like 10W30 and 5W30 (both A3/B4) in my car. This is the thinnest I have ever been, and a big relax from my GTX 20W50 & Edge 10W-60 days.

 

[Garak]

Originally Posted By: ZeeOSix
For instance, here's a couple post snips from a chat board where guys talk all day about their coolant and oil temperatures while towing a heavy trailer around the country. I doubt these trucks are WOT while towing either, but they are having to use more throttle (ie, more HP) in order to tow a heavy trailer at the same speed and up steep hills.

I wonder if adding a turbocharger to the equation is a variable we'd rather not have.

 

[Shannow]

Originally Posted By: Garak
Originally Posted By: ZeeOSix
For instance, here's a couple post snips from a chat board where guys talk all day about their coolant and oil temperatures while towing a heavy trailer around the country. I doubt these trucks are WOT while towing either, but they are having to use more throttle (ie, more HP) in order to tow a heavy trailer at the same speed and up steep hills.

I wonder if adding a turbocharger to the equation is a variable we'd rather not have.


I also wonder whether any of these hills are all attacked at the same road speed and in the same gear, as dropping a gear for a hill...changes RPM...as well.

 

[jongies3]

Originally Posted By: aquariuscsm
Heck,owning a Corvette would mean competitive driving anytime you drive it haha. I couldn't imagine putting around town like a lil old lady in one. I'd never run a CAFE oil in a high power muscle car. I'd run the 50wt rec all the time,plus M1 15W50 is dirt cheap. This just goes to further prove that thin oils are for CAFE ONLY and thicker does protect better,or else it'd say "For track or competitive driving,use Mobil 1 0W20".

There's so many people that buy them and never drive higher than the speed limit it's ridiculous. Usually old guys, drive them like an old Buick Roadmaster on a Sunday drive haha. I couldn't own a car like that and drive it like a wuss, let the beast out of the cage man!

 

[Garak]

Originally Posted By: Shannow
I also wonder whether any of these hills are all attacked at the same road speed and in the same gear, as dropping a gear for a hill...changes RPM...as well.

That, I'd wonder, too. I'm sure some of our long haul truckers here could chime in with some of their experiences. At least they might be able to tell us something over highway stretches with which they're accustomed, along with their levels of load.

I do know from my youth, turbodiesel field tractors could shoot the pyrometer through the roof if you had a big load in too high of a gear. But, the oil temperature gauges weren't worth spit for running a comparison, and I was cautioned to pay more attention to the pyrometer anyhow. How much could a glowing turbocharger skew oil temperatures, at least if there wasn't insane oil cooling like my old Audi?

 

[ZeeOSix]

Originally Posted By: Shannow
Originally Posted By: Garak
Originally Posted By: ZeeOSix
For instance, here's a couple post snips from a chat board where guys talk all day about their coolant and oil temperatures while towing a heavy trailer around the country. I doubt these trucks are WOT while towing either, but they are having to use more throttle (ie, more HP) in order to tow a heavy trailer at the same speed and up steep hills.

I wonder if adding a turbocharger to the equation is a variable we'd rather not have.


I also wonder whether any of these hills are all attacked at the same road speed and in the same gear, as dropping a gear for a hill...changes RPM...as well.


Yes, a turbo will add some more heat to the oil. Most vehicles with a turbo also have at least one oil cooler.

They don't really say specifically, but these are diesel trucks so may not really need to downshift for hills since they have so much torque and low end HP. One guy said he saw up to 240F on flat roads pulling a 10K lb trailer. I'd assume with no trailer and cruising at cracked open throttle on flat roads would give oil temp more around 200F.

But looking at the guys who tracked their Z06s, and getting the oil over 300F I'd venture lot of extra heat came from the high HP being put down on top of the higher RPM. As the cooling system gets taxed, then oil will heat up more due to combustion heat.

If someone put a large fan in front of their car to give a 70 MPH wind across the radiator and engine compartment so it was cooling effectively, and they just sat in neutral and kept the revs at 4000 RPM (only takes a slightly cracked throttle, very low HP output) for an hour, you think the oil temperature would hit 300+F?

 

[ZeeOSix]

Originally Posted By: Garak
Originally Posted By: Shannow
I also wonder whether any of these hills are all attacked at the same road speed and in the same gear, as dropping a gear for a hill...changes RPM...as well.

That, I'd wonder, too. I'm sure some of our long haul truckers here could chime in with some of their experiences. At least they might be able to tell us something over highway stretches with which they're accustomed, along with their levels of load.


I came across some information on large semi truck engine oiling systems, and they are usually designed with a very effective oil cooling system to keep oil temperatures way down. Those trucks only rev to about 1800 to 2000 RPM max, and they won't vary engine RPM much on the open interstate highways, even going up long grades with a load. They just give it more throttle to keep the speed up while climbing the grade.

Bottom line is if you can't effectively remove most of the combustion heat with the cooling system, then the oil will pick up some of what the cooling system can't. And the more HP the engine puts out, the more the cooling system has to work in removing combustion heat and it can start loosing efficiency as coolant temps rise. As the cooling system lags in efficiency, the more heat the oil absorbs and increases in temperature. That's how guys get into the death spiral of over heating on the track ... it's a domino effect. If they have a very good oil cooler, then they may not spiral to the point where they need to get of the track before the race is over.

 

[ZeeOSix]

Originally Posted By: ZeeOSix
Yes, a turbo will add some more heat to the oil. Most vehicles with a turbo also have at least one oil cooler.


Too add, those examples of guys towing heavy trailers probably also have oil coolers on their trucks since they tow all the time, and most big trucks meant for towing usually have a factory "towing package" that adds a bigger radiator, oil cooler(s) and transmission cooler. So imagine what the oil temperatures would be with no engine oil cooler when they start up a long steep hill pulling 10K lbs.

 

[Garak]

Originally Posted By: ZeeOSix
Yes, a turbo will add some more heat to the oil. Most vehicles with a turbo also have at least one oil cooler.

And this throws another variable into the equation, and makes things worse, with coolant to oil coolers, and thermostatically controlled oil coolers. If we wanted to run a test to compare load versus RPMs with oil temperature, for example, on my old Audi 200 Turbo, we would have been in trouble. It had a thermostatically controlled oil cooler, and a big one. I tested the sending unit's calibration, because I thought the oil temperatures were reading too low, but it was just the big oil cooler.

In any event, doing a lot of slow, in town driving in high heat, the oil temperature would peak around 95 C. Normal around town and freeway type driving would be lower, generally in the 80s. Now, one time, I was able to get it onto a very empty highway during a very hot night, still over 30 C, and ran at full boost, pedal to the floor, for half an hour. The oil didn't climb any higher than it did with horrible bumper to bumper traffic on the hot day. Basically, we have no idea how much the sump temperature would have risen without the oil cooler, how it would have behaved on the hot day in bumper to bumper traffic, how hot it would have gotten with my pedal to the floor, and I could not have experimented adequately with revs versus load.

My point is we have to be careful what we take from anecdotal evidence here. All kinds of behaviours can be observed thanks to turbos even, not to mention different types of oil cooling systems (which can also heat the oil significantly in their own right). When my oil temperature went to 95 C in heavy traffic with lots of idling, I can be darned sure it wasn't due to either load or RPMs. And, when both increased on the freeway, oil temperatures went down, so we have a rather useless anecdote.

 

[ZeeOSix]

Originally Posted By: Garak
My point is we have to be careful what we take from anecdotal evidence here. All kinds of behaviours can be observed thanks to turbos even, not to mention different types of oil cooling systems (which can also heat the oil significantly in their own right). When my oil temperature went to 95 C in heavy traffic with lots of idling, I can be darned sure it wasn't due to either load or RPMs. And, when both increased on the freeway, oil temperatures went down, so we have a rather useless anecdote.


Agreed on what anecdotal examples to use - maybe you guys can search for a few more beside what I found. I think the guys seeing 300+F on the track in their stock C5 Z06 is a good example because the car doesn't have a factory oil cooler of any kind, and puts out a good amount of HP. Like I said, if that same car was revved to 4000~5000 RPM while in neutral with a big fan blowing 70 MPH wind into the front of the car to keep cooling air flowing like going down the road, would the oil temperature stabilize to 300+F? I have a hard time believing it would because the amount of HP the engine is putting out is very small in that scenario (therefore the cooling system could take it) compared to putting out 300+ HP screaming around the track at 4000~5000 RPM for an hour.

In the past I have started my Z06 in the garage during the winter time and let it just idle to get to full temperature. It took awhile, but the oil temperature eventually made it to 200~205F. In a case of idling, with some time the majority of the engine's mass will get close to the bulk temperature of the cooling system, as dictated by the cooling system thermostat. In the case of the engine just idling at 750 RPM, the heat input to the oil is small from the bearing friction, instead most heat input is from the oil contacting the hot surfaces as the engine mass warms up due to combustion, and the cooling system stabilizes near the thermostat control temperature.

 

[SR5]

Originally Posted By: ZeeOSix

As the cooling system lags in efficiency, the more heat the oil absorbs and increases in temperature. That's how guys get into the death spiral of over heating on the track ... it's a domino effect.


Yes I agree with this domino effect, and I believe I have seen it myself driving through the outback in the middle of summer in an older car. The cooling system, being both water & oil, could only cope with so much heat. Push it a touch more and that extra joule of heat has no place to go and so the engine temp rises. Every rev / hp adds that "one extra joule" and in a very short amount of time the car is overheating.

I remember doing this for hours on end driving on that long straight road that connects Alice Springs to Darwin. I found that balance point where dropping my speed by only 5 kph cooled the car while raising my speed by 5 kph overheated the car. I was doing it for hours on end, in top gear, along a dead straight road.

Any extra load made a big difference, even a small load, as it spiraled up in temp. I'm sure any small increase in cooling would have helped a lot too.

Maybe the difference is in what is the dominant cause of the heat load, and what is the final origin of the heat load that causes the system to start it's climb up in temp.

 

[fredrik94087]

this [censored] thread is probably the reason why walmart was plumb out of mobil1 15w50 when I went in there today.

 

[userfriendly]

Why is the big jump from 5w30 to 15w50 necessary for all occasions? There are many in between grades.
Is it that 15w40, 20w40 and SAE 40 SOUND too thick?

Why not target the HTHS instead of the KV100C?

 

[OVERKILL]

Originally Posted By: ZeeOSix
In a case of idling, with some time the majority of the engine's mass will get close to the bulk temperature of the cooling system, as dictated by the cooling system thermostat. In the case of the engine just idling at 750 RPM, the heat input to the oil is small from the bearing friction, instead most heat input is from the oil contacting the hot surfaces as the engine mass warms up due to combustion, and the cooling system stabilizes near the thermostat control temperature.


This is why diesel engines will idle up in the winter, to heat the oil (and coolant). Since not under load they require minuscule amounts of fuel to run, so there is very little heat of combustion, ergo, to keep the temperatures up when faced with cold ambient, a high idle is utilized to generate heat via RPM/bearing friction, and of course ring/wall friction would factor in there as well.

I remember the first time I witnessed this on my buddy's former '05 Super Duty. It was about -20C out and we were standing outside talking with the vehicles running. He had driven his truck in from his place, which is a good 20Km away, so it was "warmed up". Anyways, all of a sudden his truck just idled up a significant amount and I stopped talking and looked at his truck, at which point he noted "it does that when it is cold, it can't stay hot, so the ECM commands it to idle up to make more heat". It would do this a surprising amount in the winter months I later observed.

 

[DeepFriar]

Originally Posted By: userfriendly
Why is the big jump from 5w30 to 15w50 necessary for all occasions? There are many in between grades.
Is it that 15w40, 20w40 and SAE 40 SOUND too thick?

Why not target the HTHS instead of the KV100C?


Good question!

 

[aquariuscsm]

Originally Posted By: fredrik94087
this [censored] thread is probably the reason why walmart was plumb out of mobil1 15w50 when I went in there today.


Haha I remember when Mobil discontinued M1 15W50 for awhile. Red cap went away,but they had Extended Performance 15W50,then they discontinued that one. Then Mobil announced on their web page "Back by popular demand,we reintroduce Mobil 1 15W50",which is the current "silver cap" version. I wonder how different the Extended Performance 15W50 was?

 

[Shannow]

Originally Posted By: Nickdfresh
Maybe I was a bit strong on the psuedoscience thing, but I think there is also a danger in posting dated research as gospel or the end all be all...


Been reflecting on this for a while now.

There aren't many 2016 papers on what happens when you react two moles of hydrogen with one mole of oxygen, as the science is established..a 1910 paper on the happens, the heat generation and the resultant products is still valid and current.

In many things, same is true...the warm-up paper has been referenced to as recently as 2012 that I've come across, and many of the SAE papers are referencing back to papers generated in the 70s and 80s, particularly on viscometrics. While I've been accused ofen of using old papers, it's often because once behaviours are established, there's no worth in researchers re-doing it...most of the new stuff in the area is now using finite element techniques to model the old stuff...and I've also been attahed on THAT front as using papers which numerically model behaviours.

So the old papers aren't new, and the new papers aren't engine tests...bit hard to bring "valid" information to light.

There's a couple of areas I've really been trying to find papers...for example oil gallery filling at 100F, which as you know is oft an argument issue...problem is, that all of the pumpability papers are looking at the extreme ends of pumpability, i.e. the extreme cold end of performance, as that's where the pumpability failures, engine failures and wear live. They apparently aren't putting effort into researching areas that aren't problematic in the first place.

Just some comments on posting papers...

 

[Shannow]

Originally Posted By: userfriendly
Why is the big jump from 5w30 to 15w50 necessary for all occasions? There are many in between grades.
Is it that 15w40, 20w40 and SAE 40 SOUND too thick?

Why not target the HTHS instead of the KV100C?


Yep, the high spread 50s are the new XW40 when it comes to grade silliness...

Dino 15W40 would have both the same HTHS and cold weather performance.