Rotella T6 5w-40/Dart/Texas Heat

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Originally Posted By: HKPolice
Wrong. Valvoline's oil engineer stated in a video that running thicker oil than recommended will cause hot spots to become hotter. If you knew anything about engine cooling you'll know that oil flow is crucial to cooling areas of the engine that coolant can't reach such as RIGHT UNDER THE PISTON where oil squirts to.

Will it blow the engine up? Of course not, but why argue with engineers that actually designed the engine and wrote the manual.



Originally Posted By: geeman789
Originally Posted By: HKPolice
5w40 is too thick for this regular NA 2L engine. Just keep using 0w20 or go 10w30 for better NOACK. AFAIK, the factory recommended fil is 0w20. Running thicker oil DOES have its downsides because it doesn't flow as well so hot spots in the engine will run even hotter.




What so many fail to understand is that " the engineers..." aren't necessarily the ones who "recommended" the 20 grade (weight ) oil...

And do you think a 40 grade at operating temps doesn't SQUIRT...? Or FLOW...seriously... ?

Again, at operating temps the difference between a 20, 30 or even 40 are not that huge. Why people seem to think a 40 or 50 grade is like molasses is curious. It's not, really... it's just a little thicker...

How does that Mustang GT running a 5w50 not just blow up, with that ungodly thick oil...? Their not driven on the track ALL the time, are they?

And did you know that at 40* C , your 20 grade oil is 3x thicker than the 50 grade is at operating temps...? And the engine runs just fine. For the first 15 minutes or so, EVERY OIL is way too thick, and the car survives... who'd have thunk...!
 
Originally Posted By: geeman789
Originally Posted By: HKPolice
Wrong. Valvoline's oil engineer stated in a video that running thicker oil than recommended will cause hot spots to become hotter. If you knew anything about engine cooling you'll know that oil flow is crucial to cooling areas of the engine that coolant can't reach such as RIGHT UNDER THE PISTON where oil squirts to.

Will it blow the engine up? Of course not, but why argue with engineers that actually designed the engine and wrote the manual.



Originally Posted By: geeman789
Originally Posted By: HKPolice
5w40 is too thick for this regular NA 2L engine. Just keep using 0w20 or go 10w30 for better NOACK. AFAIK, the factory recommended fil is 0w20. Running thicker oil DOES have its downsides because it doesn't flow as well so hot spots in the engine will run even hotter.




What so many fail to understand is that " the engineers..." aren't necessarily the ones who "recommended" the 20 grade (weight ) oil...

And do you think a 40 grade at operating temps doesn't SQUIRT...? Or FLOW...seriously... ?

Again, at operating temps the difference between a 20, 30 or even 40 are not that huge. Why people seem to think a 40 or 50 grade is like molasses is curious. It's not, really... it's just a little thicker...

How does that Mustang GT running a 5w50 not just blow up, with that ungodly thick oil...? Their not driven on the track ALL the time, are they?

And did you know that at 40* C , your 20 grade oil is 3x thicker than the 50 grade is at operating temps...? And the engine runs just fine. For the first 15 minutes or so, EVERY OIL is way too thick, and the car survives... who'd have thunk...!




Please quote a reference that it wasn't the engineers who decided on 20 weight oil. Otherwise it continues to be the junk that continues to be stated on this site with no proof. Everything I understand, have read and listened to interviews by design teams about OEM engine design says that all aspects is engineer driven. Of course they have to live within certain requirements like cost and efficiency. But the statement that oil requirements being chosen by marketing or some CAFE official is just internet drivel.
 
Originally Posted By: kschachn
Exactly right. The constant harping about how "CAFE made me do it" is tiring as well as specious. Unhappiness with CAFE is not a valid reason to deviate from the manufacturer's recommendation, nor is it even a technical argument. It is emotional, plain and simple.

BTW, the burden of proof is not with those that advocate what the manufacturer specifies. THe burden of proof falls on those who claim it is somehow detrimental to the engine, and why one should deviate. As far as I have seen here there is no technical reason to avoid the recommendations as given.



Some feel that a 20 grade recommendation is a " good enough..." recommendation. Good enough to get the engine past warranty, and get that small improvement in mileage that is so very important to the manufacturer. Yes... CAFE.
 
I never said it doesn't flow. I said that it won't flow as well which means less cooling for parts of the engine that coolant can't reach. Simple physics: flow oil over hot metal and it cools the metal, the higher the flow rate the more cooling effect.

Most cars run their coolant at 212F but it doesn't mean that it's 212F throughout the entire engine. There are hot spots inside that far exceed coolant temp where only the oil can reach like under the piston. This is why race cars & track cars have tons of oil coolers, so that the oil can effectively cool the hot spots. 5w40 in an engine designed for 0w20 will not cool those spots as well as 0w20 because it doesn't flow as well.

Yes, when the engine is cold the oil is easily 3x thicker or more and it still works fine you are right. But you're forgetting that THE ENGINE IS COLD, which means that it doesn't need any flow rate to cool the hot spots because there aren't any, it only needs oil flow for lubrication. THINK ABOUT IT.

Most 0w20 oils are around 8.5 cST @ 100C whereas the Rotella T6 5w40 is 13.4 cST @ 100C. Do the math: 5w40 is a full 57.6% thicker than 0w20. Again, I never said this will blow up the engine but for sure it'll be putting unnecessary heat stress on it and killing power/mpg.

Originally Posted By: geeman789
Originally Posted By: HKPolice
Wrong. Valvoline's oil engineer stated in a video that running thicker oil than recommended will cause hot spots to become hotter. If you knew anything about engine cooling you'll know that oil flow is crucial to cooling areas of the engine that coolant can't reach such as RIGHT UNDER THE PISTON where oil squirts to.

Will it blow the engine up? Of course not, but why argue with engineers that actually designed the engine and wrote the manual.



Originally Posted By: geeman789
Originally Posted By: HKPolice
5w40 is too thick for this regular NA 2L engine. Just keep using 0w20 or go 10w30 for better NOACK. AFAIK, the factory recommended fil is 0w20. Running thicker oil DOES have its downsides because it doesn't flow as well so hot spots in the engine will run even hotter.




What so many fail to understand is that " the engineers..." aren't necessarily the ones who "recommended" the 20 grade (weight ) oil...

And do you think a 40 grade at operating temps doesn't SQUIRT...? Or FLOW...seriously... ?

Again, at operating temps the difference between a 20, 30 or even 40 are not that huge. Why people seem to think a 40 or 50 grade is like molasses is curious. It's not, really... it's just a little thicker...

How does that Mustang GT running a 5w50 not just blow up, with that ungodly thick oil...? Their not driven on the track ALL the time, are they?

And did you know that at 40* C , your 20 grade oil is 3x thicker than the 50 grade is at operating temps...? And the engine runs just fine. For the first 15 minutes or so, EVERY OIL is way too thick, and the car survives... who'd have thunk...!
 
It IS CAFE. Some here just can't bring themselves to admit to the truth. Quit trying to fool yourselves into thinking that CAFE isn't really the driver to thinner and thinner oils. Industry literature openly speaks of it. Why invent a 0-16 anyways? Thats the next oil, BTW. Think about that...Why?...CAFE, period.

I have no doubt that the engineers who did design the cars actually run 5-30 and 10-30 in them, but would not openly admit it.

Back to the OP question, 5-40 will not harm your car, especially in the TX climate. Don't listen to the hysterical and uninformed here.
 
Originally Posted By: gfh77665
Back to the OP question, 5-40 will not harm your car, especially in the TX climate. Don't listen to the hysterical and uninformed here.

By the same token, the oil that was specified for the car will not harm it either.

OP - the bottom line is that you will (and have) receive countless suggestions (or opinions, which are usually stated as facts), keep in mind this is the Internet and you have wade through the information and decide what is best for you. In **most** cases, it will not matter if you use a grade that was not specified, you just have to be willing to take that risk (if one exists).
 
Originally Posted By: 2010_FX4

By the same token, the oil that was specified for the car will not harm it either.


Nobody is saying that^^^

He is just trying to use up what he already has, for one oil change!
 
Originally Posted By: gfh77665
Originally Posted By: 2010_FX4

By the same token, the oil that was specified for the car will not harm it either.

Nobody is saying that^^^ He is just trying to use up what he already has, for one oil change!

For it not to be said outright, there is certainly enough rhetoric to at least suggest that it (and I am not stating that you have--just in general). The bottom line remains that he needs to simply weigh the information and make a decision and live with the risks (if there are any).
 
Rather than feeling, I know what the manufacturer tested against and what they specify. No feelings required - only reading the owner's manual. And show me where engines are failing just past warranty. That's a merit-less argument based on no facts whatsoever.

Will the heavier oil damage anything? Of course not. But the only hysterical and uninformed are those who post unsupported arguments against what the manufacturer states, and like to blame it on the CAFE boogeyman.

Originally Posted By: geeman789
Some feel that a 20 grade recommendation is a " good enough..." recommendation. Good enough to get the engine past warranty, and get that small improvement in mileage that is so very important to the manufacturer. Yes... CAFE.
 
Originally Posted By: geeman789
Originally Posted By: kschachn
Exactly right. The constant harping about how "CAFE made me do it" is tiring as well as specious. Unhappiness with CAFE is not a valid reason to deviate from the manufacturer's recommendation, nor is it even a technical argument. It is emotional, plain and simple.

BTW, the burden of proof is not with those that advocate what the manufacturer specifies. THe burden of proof falls on those who claim it is somehow detrimental to the engine, and why one should deviate. As far as I have seen here there is no technical reason to avoid the recommendations as given.



Some feel that a 20 grade recommendation is a " good enough..." recommendation. Good enough to get the engine past warranty, and get that small improvement in mileage that is so very important to the manufacturer. Yes... CAFE.



Agreed ! those who kid themselves thinking an engineer designing an engine wants to use an oil that could potentially shear to water is doing just that kidding themselves, or trying to be "ok" with using it in there in engine. I'm not a mechanical engineer, but in the world of electronics engineering we constantly fight regulation vs functionality and endurance, we are FORCED to make decisions on every project that potentially affect the product in some way negatively in order to coincide with some regulation from big brother.

For the OP, I'm not sure that I would go THAT heavy in this engine, but I would definitely go to a 30wt.....0-30
 
Last edited:
A little extra cash in hand for not buying oil that he already had that won't hurt a thing.

Originally Posted By: Astro14
what do you gain by deviating from Dodge's recommendation?
 
Originally Posted By: HKPolice
I never said it doesn't flow. I said that it won't flow as well which means less cooling for parts of the engine that coolant can't reach. Simple physics: flow oil over hot metal and it cools the metal, the higher the flow rate the more cooling effect.

Most cars run their coolant at 212F but it doesn't mean that it's 212F throughout the entire engine. There are hot spots inside that far exceed coolant temp where only the oil can reach like under the piston. This is why race cars & track cars have tons of oil coolers, so that the oil can effectively cool the hot spots. 5w40 in an engine designed for 0w20 will not cool those spots as well as 0w20 because it doesn't flow as well.

Yes, when the engine is cold the oil is easily 3x thicker or more and it still works fine you are right. But you're forgetting that THE ENGINE IS COLD, which means that it doesn't need any flow rate to cool the hot spots because there aren't any, it only needs oil flow for lubrication. THINK ABOUT IT.

Most 0w20 oils are around 8.5 cST @ 100C whereas the Rotella T6 5w40 is 13.4 cST @ 100C. Do the math: 5w40 is a full 57.6% thicker than 0w20. Again, I never said this will blow up the engine but for sure it'll be putting unnecessary heat stress on it and killing power/mpg.


Have you ever run back-to back dyno tests with an oil that is 8.5cSt vs one that is 13.4? Do you think that the difference is seriously that significant?

Also, oil coolers reduce oil temperature, which in turn, INCREASES VISCOSITY.

Regarding flow, unless the oil pump is on the relief, flow is the exact same. Traditional oil pumps are all positive displacement (there are some new pumps that are variable displacement now too but that's another topic) which means that flow is, for all intents and purposes, the exact same between the 0w-20 and the 5w-40.

Also, the difference between something like a 0w-20 and a 20w-50 in fuel economy MIGHT be 2%, as per Mobil's documentation for the fuel economy increase using their own AFE oils:

http://www.mobiloil.com/USA-English/MotorOil/Home/Fuel_Calc.html

Originally Posted By: Mobil
Comparison based upon 2% potential fuel economy improvement obtained by switching from higher viscosity oils to a 0w-20 or 0w-30 grade. Actual savings are dependent upon vehicle/engine type, outside temperature, driving conditions and your current engine viscosity.


TEMPERATURE has a far greater effect on viscosity than the grade on the bottle. If you want to see what I mean, play around with plugging your favourite 0w-20 and 5w-40's into Widman's visc calc:

http://www.widman.biz/English/Calculators/Graph.html

And see how little temperature difference it takes to make the viscosity the exact same.

Note that I am not advocating he switch from the OEM viscosity, simply pointing out that there's a lot of "the sky is falling" happening regarding running a thicker oil which will likely do nothing other than make the engine feel a bit more sluggish during warm-up.
 
57.6 percent thicker... wow that sounds scary. And it would be, if you were starting at something WAY higher than 8 cSt... water at room temp is about 1.

As I stated earlier, a 40 grade oil at operating temps is way thinner than you might expect. And it will flow AND cool just fine...

Try it... you might like it...! Usual comments are quieter, smoother, uses less oil...

Don't hear alot of my engine runs hotter , or my mileage dropped by 25 %...!
 
Originally Posted By: OVERKILL
Note that I am not advocating he switch from the OEM viscosity, simply pointing out that there's a lot of "the sky is falling" happening regarding running a thicker oil which will likely do nothing other than make the engine feel a bit more sluggish during warm-up.

Exactly. When we look at manuals for the same vehicles outside of North America, we see different grades allowed. Of course, to me, that doesn't mean that other options are "better" or anything like that, but it certainly tells me that something isn't going to blow up by moving up a grade.

I may not be running the "optimal" grade in my G, but big deal. It isn't hurting anything. My truck's next OCI will have a more optimal 5w-30, so that will make up for everything.
wink.gif
 
Originally Posted By: Garak
Originally Posted By: OVERKILL
Note that I am not advocating he switch from the OEM viscosity, simply pointing out that there's a lot of "the sky is falling" happening regarding running a thicker oil which will likely do nothing other than make the engine feel a bit more sluggish during warm-up.

Exactly. When we look at manuals for the same vehicles outside of North America, we see different grades allowed. Of course, to me, that doesn't mean that other options are "better" or anything like that, but it certainly tells me that something isn't going to blow up by moving up a grade.

I may not be running the "optimal" grade in my G, but big deal. It isn't hurting anything. My truck's next OCI will have a more optimal 5w-30, so that will make up for everything.
wink.gif



I agree with both of you. Match the viscosity to the climate and driving conditions, they do it in other parts of the world with the same exact engines we're using here. No problems to report as far as I can tell.
 
Any oil viscosity recommendation is a compromise. My 2007 Honda manual say this...

5w20 is formulated for year round protection, and to improve cold weather starting and fuel economy.

My 2011 Subaru manual, however, says this...

Engine oil viscosity affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot weather, oil of a higher viscosity is required to properly lubricate the engine.

5w30 is recommended, but a chart showing various grades for different temps is included.

And, this...

If the vehicle is used in areas with very high temperatures, or is used in heavy- duty applications, use an oil of the following viscosity... sae 30, 40, 10w50, 20w50

However, the next year, the various oil viscosity recommendations were GONE...

Now 5w30 is required.

SAME ENGINE...

What changed...?
 
Enough time went by with a large enough sample group using 5W-30 to determine that a 30-grade oil would adequately protect the engine (at least past warranty) while also being energy conserving. Win-win for everybody (them).

Originally Posted By: geeman789
5w30 is recommended, but a chart showing various grades for different temps is included.

And, this...

If the vehicle is used in areas with very high temperatures, or is used in heavy- duty applications, use an oil of the following viscosity... sae 30, 40, 10w50, 20w50

However, the next year, the various oil viscosity recommendations were GONE...

Now 5w30 is required.

SAME ENGINE...

What changed...?
 
Wow, total lack of comprehension. I'm not replying anymore after this post because obviously you can't read.

1) I NEVER said that the sky is going to fall using a thicker oil, in fact I said TWICE that it'll run fine. Just that hot spots WILL get hotter & mpg will decrease. No one understands how engine cooling works it seems.

2) 8.5 cST vs 13.3 cST is 57.6% thicker that is a fact, DO THE CALCULATION YOURSELF.

3) I said that RACE CARS & TRACK CARS have oil coolers to keep the oil temps in check in order to provide adequate cooling for hot spots inside the engine. Yes, cooling the oil increases viscosity but RACE CARS run so hot that the oil will overheat without them.

You guys have no concrete proof of any advantage for running 5w40 over 0w20, all opinions. I have math & thermodynamics to support my claims. Again, I NEVER said that using a thicker oil will blow up your engine, but hot spots will run hotter & other quirks like valve timing MIGHT not work causing a check engine light.

Want more proof? How about Valvoline engineers?

http://youtu.be/FXqkOZAkXZw?t=10m20s


Originally Posted By: OVERKILL
Originally Posted By: HKPolice
I never said it doesn't flow. I said that it won't flow as well which means less cooling for parts of the engine that coolant can't reach. Simple physics: flow oil over hot metal and it cools the metal, the higher the flow rate the more cooling effect.

Most cars run their coolant at 212F but it doesn't mean that it's 212F throughout the entire engine. There are hot spots inside that far exceed coolant temp where only the oil can reach like under the piston. This is why race cars & track cars have tons of oil coolers, so that the oil can effectively cool the hot spots. 5w40 in an engine designed for 0w20 will not cool those spots as well as 0w20 because it doesn't flow as well.

Yes, when the engine is cold the oil is easily 3x thicker or more and it still works fine you are right. But you're forgetting that THE ENGINE IS COLD, which means that it doesn't need any flow rate to cool the hot spots because there aren't any, it only needs oil flow for lubrication. THINK ABOUT IT.

Most 0w20 oils are around 8.5 cST @ 100C whereas the Rotella T6 5w40 is 13.4 cST @ 100C. Do the math: 5w40 is a full 57.6% thicker than 0w20. Again, I never said this will blow up the engine but for sure it'll be putting unnecessary heat stress on it and killing power/mpg.


Have you ever run back-to back dyno tests with an oil that is 8.5cSt vs one that is 13.4? Do you think that the difference is seriously that significant?

Also, oil coolers reduce oil temperature, which in turn, INCREASES VISCOSITY.

Regarding flow, unless the oil pump is on the relief, flow is the exact same. Traditional oil pumps are all positive displacement (there are some new pumps that are variable displacement now too but that's another topic) which means that flow is, for all intents and purposes, the exact same between the 0w-20 and the 5w-40.

Also, the difference between something like a 0w-20 and a 20w-50 in fuel economy MIGHT be 2%, as per Mobil's documentation for the fuel economy increase using their own AFE oils:

http://www.mobiloil.com/USA-English/MotorOil/Home/Fuel_Calc.html

Originally Posted By: Mobil
Comparison based upon 2% potential fuel economy improvement obtained by switching from higher viscosity oils to a 0w-20 or 0w-30 grade. Actual savings are dependent upon vehicle/engine type, outside temperature, driving conditions and your current engine viscosity.


TEMPERATURE has a far greater effect on viscosity than the grade on the bottle. If you want to see what I mean, play around with plugging your favourite 0w-20 and 5w-40's into Widman's visc calc:

http://www.widman.biz/English/Calculators/Graph.html

And see how little temperature difference it takes to make the viscosity the exact same.

Note that I am not advocating he switch from the OEM viscosity, simply pointing out that there's a lot of "the sky is falling" happening regarding running a thicker oil which will likely do nothing other than make the engine feel a bit more sluggish during warm-up.
 
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