KLdy

I went on and ask about our oil and everything

this is his response

and this is his blog

https://540ratblog.wordpress.com/

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Hi 540 Rat

Your site is very helpful

but could you please be so kind to answer me some questions

I have a C7 Corvette, my engine temp is stable now with the new radiator,but my oil temp gets up to around 260-270 on the track.
I want the most anti wear protection but I heard you need to have a certain amount of viscosity for engine protection.
I was using M1 15W-50 but it did not seems to be the best choice for my base corvette wetsump, and M1 0W-40 does not provide more wear protection than 5W-30

Currently Im using 5W-40 from liqui Moly, could you please test their thermal breakdown points in the future?

Its looks like Pennzoil-Ultra (Black Bottle) is the one to go with the 90,000+PSI for wear protection, and high thermal breakdown point 285F
This seems like the oil for me, but I am just worried that when it gets to 270 the oil is too thin? Will that be the case? Should I look for a 40 oil instead like what I am doing right now?

Last question, as you mentioned using prolong engine treatment which contain chlorine, which could cause corrosion to the engine parts and bearings, does that mean I shouldnt use it? Do I have another option? like an additive without chlorine? Sorry about my lack of knowledge

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Hi Kevin, it’s good to hear from you.

Motor oil viscosity is NOT what determines wear protection. That is just an old MYTH, that some people who don’t understand anything about motor, still believe. So, ignore anything you’ve heard about needing thick oil for wear protection, because using thick oil is one of the worst things you can do to your engine.

Consider the actual Engineering viscosity test data that came out of my Motor Oil Testing:

20 wt oils rank between number 3 and 172

30 wt oils rank between number 1 and 183

40 wt oils rank between number 22 and 171

50 wt oils rank between number 23 and 180

So, as you can see, the various oil viscosities all overlap each other regarding their wear protection ranking position, which clearly shows that oil viscosity does NOT play a role in an oil’s wear protection capability. An oil’s wear protection capability is determined by its base oil and its additive package “as a whole”, with the primary emphasis on the additive package, which contains the extreme pressure anti-wear components. And that has nothing to do with viscosity.

Using thicker oil will simply reduce critical oil flow for no good reason. And oil flow is lubrication. Plain bearings, such as rod and main bearings, are lubricated by oil flow, not by oil pressure. Oil pressure is NOT what keeps these parts separated. Oil pressure is a measurement of resistance to flow, and the pressure serves to supply the oil to the clearance between the bearings and the crankshaft journals, and of course throughout the engine. The crank journals and the bearings are kept separated by the incompressible hydrodynamic liquid oil wedge that is formed as the liquid oil is pulled in between the spinning parts. As long as sufficient oil is supplied by reasonable oil pressure, no wear can occur. And the higher flow rate of thinner oil, supplies more oil volume to the main and rod bearings, which also helps ensure that the critical incompressible hydrodynamic liquid oil wedge is always maintained.

Thinner oil will of course flow out from the bearing clearance quicker than thicker oil will. But, by making sure the engine always generates “sufficient oil pressure”, the oil supply will always stay ahead of the oil flowing out, which will maintain that critical incompressible hydrodynamic liquid oil wedge.

Oil flow is also what carries heat away from internal engine components. Those engine components are DIRECTLY oil cooled, but only INdirectly water cooled. And better flowing thinner oil will keep critical engine components cooler because it carries heat away faster than slower flowing thicker oil can. This is especially important with plain main and rod bearings, since the flow of oil through the bearings is what cools them. If you run thicker oil than needed, you will needlessly drive up engine component temps.

Here are some comparison numbers from an 830 HP road race engine on the track:

15W50 oil = 80 psi = 265* oil sump temperature

5W20 oil = 65 psi = 240* oil sump temperature

Here you can see how the thicker oil flowed more slowly through the bearings, thus getting hotter, driving up bearing temperatures and increasing sump temperatures. And the thinner oil flowed more freely and quickly through the bearings, thus cooling and lubricating them better than thicker oil. And this means the oil coming out from the bearings, and going into the sump, is also cooler. And that is why we see the cooler sump temps with this road race engine example.

If an engine is running hot, use a thinner oil to increase flow, increase internal component cooling, and help keep sump temperatures down. Keeping oil temps down is important to help keep oil below the threshold of thermal breakdown.

Almost no engine should ever need to run oil thicker than a multi-viscosity 30 weight. The lower the first number cold viscosity rating, the better the cold flow. For example, 5W30 flows WAY better cold than 15W50. And the lower the second number hot viscosity rating, the better the hot flow. For example, 5W30 flows WAY better hot than 15W50. Thinner oil will also typically increase HP because of less viscous drag and reduced pumping losses, compared to thicker oils.

The churning action of rotating and reciprocating internal engine components, along with oil spraying out from between pressurized components, and overall windage, all contribute in varying degrees, to causing the engine oil to become aerated, which is exhibited by air bubbles/foam in the oil. Air bubble-filled foamy oil, is what typically causes engines running on a dyno to experience oil pressure drops, assuming they have acceptable oil drain-back from the top end, and are keeping the oil pump pickup submerged. Also, air bubble-filled foamy oil, is what typically causes engines being run hard in cars, to experience drops in oil pressure, assuming the oil pump pickup is still submerged in oil. And if that isn’t bad enough, air bubble-filled, foamy oil cannot lubricate critical internal components properly. For proper lubrication of critical components, you need incompressible “liquid” oil, NOT compressible air bubble-filled foamy oil.

This is an issue to take very seriously, if you want to provide your engine with the best possible lubrication protection. If this aerated oil issue is bad enough, it can cause wear, damage or outright engine failure. And it can be extremely difficult to diagnose, in the event of an outright engine failure. Because when you take the engine apart for examination, you typically can’t find anything wrong at all, other than say the rod and/or main bearings that failed. That’s because the air bubbles/foam are long gone by then.

Heavy thick oil such as 15W50, is of course 50 weight oil at normal operating temperature, is slower to release and eliminate air bubbles/foam, than thinner oil such as 5W30 which is 30 weight oil at normal operating temperature. Motor oils do of course contain anti-foaming agents to help control (though not altogether eliminate) air bubbles/foam. But, the air bubbles that will still be present in the oil anyway, have to travel through the oil to be released. And thicker heavier oils slow down that process, leaving compromised lubrication. Adding aftermarket oil treatments that thicken the oil more, makes aeration issues even worse, by causing further slowing of air bubble release. But, thinner oil such as 5W30, allows air bubbles to travel through the oil and be released quicker, making it a better viscosity choice to fight motor oil aeration issues, and provide the best possible lubrication protection for your engine.

Thinner oil will also drain quicker back to the sump, to help keep the oil level high enough to prevent the oil pump pickup from sucking air during hard braking or cornering, in wet sump systems.

Your engine was designed to use 5W30, so it should NOT use any oil thicker than that. So, I agree that the following oil would be an excellent choice for your needs:

5W30 Pennzoil “ULTRA” Platinum, Pure Plus Technology, made from pure natural gas, API SN, GM dexos 1 approved = 99,039 psi

This oil comes in a DARK GRAY bottle with a blue vertical stripe on the label. Do NOT confuse this oil with the ordinary Platinum oil, because the ULTRA version is much better.

The psi value of this oil, which came from testing it at the normal operating test temperature of 230*F, put it in the OUTSTANDING Wear Protection Category.

I also tested this oil at the much higher temperature of 275*F. At that elevated temperature, any hotter and thinner oil is expected to experience a drop in Wear Protection Capability. But, this oil had only an extremely small 2.7% drop in capability, the smallest drop I have seen. And at that reduced value down to 96,363 psi, this much hotter and thinner oil was still in the OUTSTANDING Wear Protection Category.

5W30 Pennzoil Ultra Platinum, API SN, GM dexos 1 approved, synthetic = 290*F onset of thermal breakdown.

You should NOT use any aftermarket additive, because they most often ruin the oil by making it worse overall, than it was to begin with, no matter what it may or may not do regarding wear protection.

5W40 Liqui Moly Leichtlauf High Tech Oil, synthetic = 69,580 psi, which is a fairly poor performance, that ranks the oil 141st out of 183 oils tested so far. I no longer have that oil on hand, to perform any further testing. Because of its poor performance, I would not recommend using that oil in your engine, when there are so many other, far better performing oils, readily available.

Thanks for getting in touch,

540 RAT

KLdy

Im switching to Pennzoil Ultra Platinum Full Synthetic 5W30 SN Motor today

and this is detox 1 Approved too

rmerritt

Really interesting and well articulated article/response to you.


Particularly interesting that he is contradicting what GM puts in the manual - 15W-50 for track or road racing use (page 228).

KLdy

Yes I know right?

but i i might keep using M1 15W-50 because of the warranty

on the other hand, people do trust GM more since trey actually build and tested the car, but remember they are also the person that brought us the overheating C7s, and a defected 8Speed which were claim to be better than PDK...

KLdy

but GM Didn't even bother testing with the m1 0W-40..

Steve_R

Dexos, not detox.

KLdy

ops lol

LDB

The Ratblog guy gets cited every now and then on the forum. Trouble is, he’s a one note Charlie. According to him, it’s all about his wear measurement. I won’t deny that’s one aspect of a good oil, but it’s certainly not the only one. There are many others, from oxidation, pH, thermal, and viscosity stability, to detergency, to friction characteristics, and that’s just the start of the laundry lists. And even on wear measurements, the fact that an oil is best at some specific combination of oil temperature and characteristics of the testing rig doesn’t mean it’s best at all such points. A good way to think about it would be if your doctor judged your health totally on the basis of your cholesterol, never mind your weight, physical condition, smoking history, diseases you may have had currently or in the past. He tells you that the one and only, total indicator of your health is cholesterol. That position by a doctor would be simply preposterous, and I’m pretty sure most people would be bright enough to avoid such a doctor.

A second questionable position by Ratblog is the idea that higher viscosity oil isn’t needed for higher temperature. That seems almost as preposterous as his wear measurement thing. Oil thins out as it heats up. Every reputable oil information source that I know of will tell you that if you are racing, with oil temperatures in the upper 200’s, you need heavier oil (40 or 50 weight). That way, the heavier oil in the upper 200’s has the same viscosity at the actual oil temperature as a 30 weight oil would have in the oil’s normal street temperature of the lower 200’s. An occasional burst of high speed driving that sends oil temp to the upper 200’s for brief periods is ok for 30 weight oil, but sustained operation in the upper 200’s with 30 weight oil is simply not bright. The only way I could assume that Ratblog’s viscosity comments would make any sense would be if he is assuming that most of the time, the car in question is driven on the street, with only occasional racing. In that case, since it is true that 50 weight would be too thick for the street, the 50 weight might do more damage during the car’s usual street use than 30 weight would do in the car’s occasional racing use. A very real issue that is faced by someone who uses his car for both racing and street is whether he needs to change oil as he changes between racing and street. To some extent, you can compensate for that by using a very wide spread oil like 0W-40 or 10W-50, but that brings in issues with stability of the VI improver that is needed to make those oils. So there is no easy answer to the question proper oil for using the same car on the street and track. You either change it as you change between street and track, or you introduce some risk on one or the other application.

KLdy

I see I forgot to mentioned that tho.
I believe GM forces us to use 5W-30 because it generally has a better fuel economy. I really wanna use 0W-40 because that seems like a good street oil and enough viscosity for track.
and a lot of European sports cars uses 0W-40 I m just wondering why we can't.
and according to one of the forum members he's actually not using 15W-50, but he kept using 5W-30 M1 because the oil test he did after a track day showed hardly any issues with the oil.

KLdy

his post is right here and said that the 5W-30 did not degrade at 290F, despite 540 Rat have not directly talk about temperature and viscosity, he does have some good points on high Zinc oils, high zinc contents doesn't mean wear protection

#16
http://www.corvetteforum.com/forums/...r-upgrade.html

juanvaldez

I betcha the engineers at Corvette don't understand this stuff which is why they recommend 15w50 for the track.

BenCasey

Some great posts!

The other concern I would have is with the oil "sheer" (i think thats what it was called) or when sustained high temps lower the upper viscosity rating; as in a 50 weight oil would lose that rating after sustained driving. Aside from 260 degree 50 weight oil being similar to 30 weight, my understanding is that after X time the weight would be even less.

I'm not making a point, I'm hoping someone might know more about that.

I have to assume the people at GM know a thing or two about oil. I can't imagine the 15-50w was mostly a guess..

LDB

The best viscosity for any given engine is a function of many things, the most important two being the bearing/lifter characteristics of that particular engine, and the temperature range of the oil at various points within the engine (as opposed to the single point at which the oil temperature gauge sits). You can be sure that GM engineers are intimately familiar with those characteristics of their engines, as well as how viscosity of oil changes with temperature, so unless you believe they are incompetent (and if you believe that, why did you buy a GM car), it seems like their recommendations for their engines ought to be the most credible of various sources. It’s very easy for me to believe that different engine characteristics mean that 30 weight is best for Vettes on the street while 40 weight is best for BMW’s on the street, while 50 weight is best for either one of them on the track.

As far as thermal stability, any good synthetic base oil is thermally stable well past 300. Yes, it thins out as temperature increases, but that’s not degradation. That’s just the characteristic of most fluids. Hotter = thinner, colder = thicker. You can go through any number of heat up and cool down cycles, and the viscosity at any given temperature is always the same. The trick is to match the viscosity to the temperature in the engine.

Viscosity degradation occurs due to degradation of the VI improver additive. VI means viscosity index, and is a measure of how much viscosity changes with temperature. In the old days with dino oil, there was quite a bit of change, and today’s single weight dino oils still have that high amount of change. So with a single weight oil, it is very important to operate in a narrow temperature range, because if you deviate much from it, the viscosity will be a lot different than ideal. Multi grade oils like 5W30 don’t change viscosity as much with temperature. A 5W30 is the same viscosity at 212 degrees as a 30 weight single grade oil, but at 32 degrees, since the viscosity changes less with temperature, it is the same viscosity as a 5 weight single grade oil. This has obvious benefits for cold starts, but also has benefits for very hot operation into the upper 200’s, because just like it doesn’t thicken up as much when it gets cold, it doesn’t thin out as fast as it gets extra hot. The fly in the ointment is that with dino oils, VI improver additive is needed to make multi grade oils, and those additives are not as stable as the base oil. They are very large molecules with long side chains, and the long side chains give them reverse viscosity behavior, namely, they get thicker when they get hotter. That happens because the long side chains extend when they get hot, and this raises viscosity. Trouble is, those long side chains can shear off, and if they do, the VI improver additive no longer works.

By far the biggest single advantage of a full synthetic is that it has higher starting VI than dino oil. So you can make a full synthetic up to about a 25 spread (difference between W and normal number) without VI improver additive. Thus, unlike dino oil, where you need VI improver to make 5W30 or 15W40 (both having 25 spread), you could make either of those grades in a full synthetic without VI improver. But the very wide spread full synthetics, like 0W40 (40 spread) or 15W50 (35 spread) still need VI improver, and are thus subject to VI improver shear. And if it shears, you lose viscosity on the high number, not the W number, so degrading to a 25 spread, the 0W40 could become 0W25, and the 15W50 could become 15W40. Bottom line is that if you want to use those extra wide spread oils to give you a better ability to stay at proper running viscosity with the same oil on both the street and track, you are exposing yourself to some risk of viscosity loss due to shearing, or degradation of the VI improver additive that is required to make those oils.

Where does that leave you? GM recommends 5W30 for street, 15W50 for serious track work, and since they designed the engine, know its characteristics, and are presumably not incompetent, I’d believe them. If you are in between, with more track work than you feel comfortable with 5W30, but not wanting to do the aggravation of changing oil all the time, 0W40 might be a good compromise. But since it has a lot of VI improver additive to get a spread that wide, I wouldn’t run it past 4 or 5000 miles. And I’d also caution you that you might get in warranty trouble with GM going that route.

BenCasey

Great post, very informative, very appreciated.

For now, Chevy changes my oil (have 1 more free one). I was considering moving to 0w-30 mobil1 when I do my own.

I don't think this would matter much with, what must be, minimal VI improver and/or oil sheer. Thoughts? Yeah, I'm overthinking it. But if it's right there at the same price with better startup protection, why not?

Thanks LDB!

LDB

I don’t see any huge factors in either direction. Yes, 0W30 would be slightly better on startup and slightly better on the ultra hot end too (due to flatter viscosity/temp curve). But I don’t think San Jose’s weather ever gets very cold and you don’t mention using it on the track, so assuming you stay away from heavy throttle until warm, your need for those factors doesn’t seem very great. The risk is that the modest amount of VI improver needed for 0W30 could degrade, and if it did, you’d be left with 0W25, which is a bit on the light side. That risk is low if you change oil at 50% remaining life on the monitor, but would increase a bit if you run the oil all the way to the oil monitor life. For my part, I live in Houston, and ran 5W30 in my three Vettes from 1990-2010, as well as my current CTSV, usually running down to 10-20% remaining on the oil life monitor on all of them. Bottom line, while I’d stick with 5W30, I wouldn’t call 0W30 seriously wrong. Part of my attitude is that I lived through some of the early horror stories with VI improver, so I’m still a bit gun shy about it. But though still not as robust as the base oil itself, VI improver is vastly better now than it was back then.

KLdy

Thank you for the detailed response

Yes that is what I was concerning about too, that is why I was using 15W-50 in the first place

But I do an oil change after track anyways, I just dont wanna swtich between two oils.

After installing the oil cooler I believe the temp will be in an acceptable range for not to use the 15W-50, but instead use the 5W-30 which provides better flow and according to the post...has a better antiwear protection.

at the sametime lower oil temp is always a good thing.

btw, the only concern Tadge had about leaving the 15W-50 in the car I believe was the CATS, because 15W-50s high ZDDP Content it will increase the "Wear" for CATS.

so if anyone doesnt care about the cats just leave them in

KLdy

It is not that I dont trust GM Engineers, as I have no knowledge at all about how their department works.

But based on my C7 Experience .

GM has a great mechanical engendering department...e.g. my flawed but a good 8SPD Transmission, IT COULD MATCH THE PDK Easily, it shifts so fast, but really bad software

but their software engineers are absolutely terrible based on all the electronic stuff that doesn't work the correct way in my car, and lots of others have experiences, I mean it has some great idea but it feels like its done out of a windows 98..if you know what I mean.

so I think based on that GM have weakness as well, so for warranty purpose Im sticking with the 15W-50 , but I believe that 15W-50 is commandeered on the track prep guide, but not required correct?

LDB

I can’t speak to GM’s warranty rules. If I had a car that I wanted to track, I would be sure to understand that before deciding what to do. You are correct in assuming that an oil cooler would reduce the need for 15W50. I wouldn’t be worried about 5W30 unless oil temp was consistently over the 250-260 range for extended periods of time. But whether GM would accept that logic for warranty purposes would be their decision, not mine. I do see a possible problem with adding an oil cooler, and then continuing to use 15W50. That would mean that on the street, with the added cooling from the cooler, your oil might be seriously too heavy. Or another way of saying it is that I disagree with your statement that lower oil temp is always a good thing. If you double dip by adding an oil cooler to cool things down, but then stick with a heavy oil which is meant to counter high oil temps, you could very easily have an oil that is way too heavy for the oil temp that the engine actually runs.

I agree that GM is not perfect, particularly their electronics. We quickly sold my wife’s Caddy XTS at a big loss because the CUE system was so horrid. But I’ve never had any issues with their engines. All companies, including the oil company I retired from, have their blind spots. One just has to resist the temptation to think they are screwed up everywhere because they mess up in an area here and there.

KLdy

Yes I agree

I will test it out later on when everything is transferred from my Base A8 to a Z51 M7

Just deciding the setup right now

juanvaldez

Rule of thumb on race engines 10 wt/1,000 rpm. I don't know if it holds for more modern engines.