5w-30 versus 0w-40?

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FWIW, I've been using 0w-40 mobil 1 in our 2000 Honda odyssey for the past 5 years without a problem - specs 5w-30 on the oil cap and manual. Engine actually sounded a bit quieter as I recall when I first started using it. Have noticed that it holds up better over a change interval than the 5W-30 mobil 1 did- Gets less dark and smelly, and has more lubricity when felt between the fingers. (I know, it's not a scientific test like oil sampling, but it's still definately noticeable). I think that the extended drain euro specs on this oil are superior from a longevity standpoint than the SAE only spec'd 5W-30, and accounts for the better performance that I've seen in my application. Presently the van has 190,000 km on it and still runs well and uses little to no noticable oil between changes (approx. 6 mths / 8000 km).

hope this helps.
 
rondoggnuts said:
^Good point, I didn't know that it happened with the same engines.[/quote

Oh yes. Here in North America there is a tendency to use 20 grades due to CAFE however those same engines in Europe and Australia will specify a thicker oil.
Personally I don't see any harm going a grade thicker and M1 0w-40 is a very tough to beat oil. German castrol is another one that is difficult to beat in an application that calls for a 20 or 30 grade.
I'd use either of those 2 across the board and will be in both my mustangs. I beat on em hard and those 2 are likely 2 of the best oils on earth.
Today's 20 grades are very good as well and I'm slowly gaining confidence in their use however its tough to shake the thicker is better idea that's been pounded into me for decades.
Today's engines will operate on a variety of different grades and I think government has more to do with the oil spec than the manufacturer.
Jmo
 
^^Thanks guys, it looks like I need to come back to the wealth of knowledge on this board. I got a hold of a dozen qts GC green myself some years back from another member. I noticed that GC was at the upper end of the 30 grade scale, and M1 is not far off, at the lower end of 40 grade. I had no idea that 20 was okay, but I've made exceptions in Toyota engines that make only short trips. But I was worried that it could be a problem if it was at operating temp for too long/too often. I take it I got the wrong impression years ago, or that times have changed?

Another issue people like to bring up is voiding the warranty. But I can't imagine them testing the oil's viscosity before accepting a warranty claim. I guess it would depend on the manufacturer, but I'd bet the farm that my Lexus dealer wouldn't question my receipts as proof, and I have plenty from when I've stocked up for other vehicles that get 30 grade.
 
The two are for all practical purposed the same thickness, as M1 0w40 will shear down to a thick 30 rather quickly from what I've seen, and GC tends to be very shear stable. Use whatever you can get cheaper.
 
Originally Posted By: rondoggnuts

But the difference is that BMW's call for it, while my engine specifies 5w30. The posts above say that it isn't any "better," so I'm asking if it's any "worse," if the price was the same?


The thick vs thin argument gets people around here really worked up.

You will see a slight lose in fuel economy and a potential complication for warranty work with a 40 wt oil. M1 0W40 does provide better engine protection than M1 5W30.
 
^Thanks Gabe, for confirming the protection issue. As for the gas mileage, I definitely took a hit. But I can never be certain about whether I can attribute a significant portion of my losses to the motor oil (e.g. short trips, more city driving than before, lead foot, new aftermarket air filter, etc), in spite of the measurable results I got many years ago. I was using FP-Plus, TCW-3, Lucas UCL, MMO, acetone/xylene, etc, but not all at once (obviously). I went from ~20 MPG to ~22 MPG, but there's no way I can attribute it to that. A better experiment would include drivers totally oblivious to the contents added to its fuel. Even then, it's hard to be sure that my habits stayed consistent. I'm essentially a broken person, but sleeping soundly outweighs the loss, to me. Regardless, I'm happy to get such wonderful advice on here. Many thanks to all of you.
 
Originally Posted By: rondoggnuts
^^Thanks guys, it looks like I need to come back to the wealth of knowledge on this board. I got a hold of a dozen qts GC green myself some years back from another member. I noticed that GC was at the upper end of the 30 grade scale, and M1 is not far off, at the lower end of 40 grade. I had no idea that 20 was okay, but I've made exceptions in Toyota engines that make only short trips. But I was worried that it could be a problem if it was at operating temp for too long/too often. I take it I got the wrong impression years ago, or that times have changed?

Another issue people like to bring up is voiding the warranty. But I can't imagine them testing the oil's viscosity before accepting a warranty claim. I guess it would depend on the manufacturer, but I'd bet the farm that my Lexus dealer wouldn't question my receipts as proof, and I have plenty from when I've stocked up for other vehicles that get 30 grade.


When making a warranty claim one of the techs first tasks is to sample the oil in the sump. It's the oem looking for a reason to blame the consumer and flip the script.
It could be an electrical issue but the dealers instruct their employees to start at hearing potential evidence.
 
Originally Posted By: NateDN10
Originally Posted By: dparm
Eh, the KV values are not really that important. I would judge the oil's characteristics by MRV/CCS, VI, and HTHS.

Yes, but VI is based on the KV at 40C and 100C.

That's true but VI is a calculation of the rate of change in viscosity so the fact that it is derived from two kinematic measures is not critically important.
It would be theoretically better if both the 40C and 100C viscosity measures were made using the HTHS methodology but I doubt there would be much difference in VI values; i.e., a high VI oil is still going to be a high VI oil and a low VI oil still low.

The point is KV spec's vary a lot based on oil chemistry alone, that's why if you know the much more relevant (and accurate) other viscosity measures; namely, MRV/CCS, VI and HTHS the KV spec's are best ignored.
 
When making a warranty claim one of the techs first tasks is to sample the oil in the sump. It's the oem looking for a reason to blame the consumer and flip the script.
It could be an electrical issue but the dealers instruct their employees to start at hearing potential evidence. [/quote]


Does your tinfoil hat interfere with cell phone reception? Or can you wear it all the time? In 10 years at a dealership the only time I've seen oil samples called for was on blown engines. On one the owner had no maintenance records so they wanted a sample. Another I saw was a blown up diesel that had been run with a nitrous and water methanol injection system, which the customer denied even though he forgot to take the hoses out when he removed the rest of his set-up.
 
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Another thing that helps me choose between 5w30, 5w40 or 0w40 is the operating oil temperatures.

My rule of thumb is this: consistent >100C = xw-40, 100 or
Factors like fuel dilution, external temps and motor age should also be taken into account.
 
Originally Posted By: Clevy
Originally Posted By: rondoggnuts
^^Thanks guys, it looks like I need to come back to the wealth of knowledge on this board. I got a hold of a dozen qts GC green myself some years back from another member. I noticed that GC was at the upper end of the 30 grade scale, and M1 is not far off, at the lower end of 40 grade. I had no idea that 20 was okay, but I've made exceptions in Toyota engines that make only short trips. But I was worried that it could be a problem if it was at operating temp for too long/too often. I take it I got the wrong impression years ago, or that times have changed?

Another issue people like to bring up is voiding the warranty. But I can't imagine them testing the oil's viscosity before accepting a warranty claim. I guess it would depend on the manufacturer, but I'd bet the farm that my Lexus dealer wouldn't question my receipts as proof, and I have plenty from when I've stocked up for other vehicles that get 30 grade.


When making a warranty claim one of the techs first tasks is to sample the oil in the sump. It's the oem looking for a reason to blame the consumer and flip the script.
It could be an electrical issue but the dealers instruct their employees to start at hearing potential evidence.


Neer ever have I or any of my collegues have to do this, and we got our fair share of total loss engines under warranty. You either have a full service history, or you don't.
 
Originally Posted By: OceanRuns
Let's say a vehicle calls for 5w-30. Let's say you're using synthetics. Assuming you aren't trying to push to a very high mileage OCI, is there anything 0w-40 wouldn't do better? If a vehicle was built before 0w-40 was an option, might they have spec'd it for that were it available then?

My (limited) understanding is that the greater the spread, the more the oil is 'propped up' by additives that can break down. Is this accurate? So, assuming you're changing oil within 5-7.5k miles and 12-18 months, would the 0w-40 do better?

(Vehicle is 3.4, Toyota T100. But am curious in general also.)


Why would u be looking at 0W-xx oil if u are in California , unless u are making frequent ski trips to big bear or Tahoe.
I can understand wanting to go a little thicker to a 5W-40, instead of the 5W-30 spec for ur truck. But to me a 0W-xx seems really unnecessary for someone in FL, or most of CA. A 5W-40 synthetic would be perfect for that old engine. U could pick up an HDEO 5W-40 for cheaper than any name brand 0W-40 synthetic that u are looking at.
 
My T100 3.4L has loved 15w40 rotella, 10w30 M1 HM, RTS 5w40, ect. Its at 240k and needs a bit thicker oil to have a good oil pressure at idle. (Yes, it has a real oil pressure gauge.) I actually got some of my best MPG in the summer on Rotella 15W40. If you have a lot of miles, being in the 40 weight range is probably a good idea for these engines. My current go to oil is the M1 10w30HM since it is a heavy 10w30 and the high mileage additives help keep my oil leak to a minimum.
 
0W-40 guarantees that you'll be using a synthetic or a near-synthetic. 5W-30, OTOH, comes in a whole rainbow of formulations and is a product which is "cost-managed" to the lowest price point possible.

So if its simply a matter of choosing 5W-30 versus 0W-40 in terms of picking a retail product off the shelf, I'd take the 0W-40 any day of the week.

However, if you are comparing truly similar products (ie: Mobil-1 5W-30 versus Mobil1 0W-40), then I'd be inclined to go with the 5W-30, unless cold starts are anticipated. In which case, you'd be back to wanting the 0W-40 for more aggressive protection during startup.

It might be worth noting that on account of being forced to use higher VI base-stocks to formulate the 0W-xx oils, that they tend to have not only the superior low-temperature characteristics, but also superior high-temperature characteristics. I know this is counter-intuitive, but a review of the data sheets will reveal that the 0W-xx products tend to outperform on both ends of the spectrum.
 
Originally Posted By: OceanRuns
Let's say a vehicle calls for 5w-30. Let's say you're using synthetics. Assuming you aren't trying to push to a very high mileage OCI, is there anything 0w-40 wouldn't do better? If a vehicle was built before 0w-40 was an option, might they have spec'd it for that were it available then?

My (limited) understanding is that the greater the spread, the more the oil is 'propped up' by additives that can break down. Is this accurate? So, assuming you're changing oil within 5-7.5k miles and 12-18 months, would the 0w-40 do better?

(Vehicle is 3.4, Toyota T100. But am curious in general also.)

I think you are comparing apples and oranges.
0W40 is il that is produced for European and some other high performance vehicles. It is MUCH more thicker than regular 5W30 oils that you can buy in Wal Mart etc.
Now if you are comparing 5W30 and 0W30 oils that are made for European cars, than difference is not big.
 
Which oil is "better"?:
Mobil 1 Annual Protection 5W30, 5 qt -- $40
Mobil 1 0W-40 Advanced Full Synthetic Motor Oil, 5 qt. --$25

I have a 2007 Saab 9-3 2.0T -- I believe the owner's manual calls for 5W-30, but most "Saab guys" use 0W-40.

Is either one group IV or V ; "fully" POA or ester based?
To me it's seems like the one that cost 60% more should be the better oil or should be more "synthetic", also it suppose to last longer.

regardless of cost which one is "better"? Going to be winter in NH sooner.

More of my "thinking":
What seems to happen in American markets or markets in general is some one created hype about something (i.e. a brand, a model, a spec, a certification, but can be literally anything) then the corporations make that product cheaper and cheaper and it has little do with the safety/performance of the original products.
 
You have a Saab, you have a possible oil pump pick-up screen issue with clogging due to coking oil. It has to do the placement of the CAT next to the oil pan. You need a quality synthetic to combat the coking issue.

Dexos I, Gen II oils are good at that. Rotella T6 is good. Most of the full synthetic HDEO's are fine. Viscosity is not the issue as long as it's xW-30 or xW-40. As the miles accumulate, it prolly needs xW-40 for summer ...

Pick an oil with low NOACK
smile.gif
 
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One would think all things being equal, the 0w-40 should provide better overall protection than a 5w-30. That could be a metaphor..
Then of course will the engine know the difference??
 
In really hot climates the engine will know the difference between the 5w30 and 0w40.

I had a mechanic tell me once "You need thicker oil, then the oil leak may stop because your engine is older the 0w 40 is no good as it is designed for tight tolerance motors" (Mechanic of over 30 years experience).

I asked what I should get, he said you need something a little thicker and said to get like a 15w 30.

I call up 2 oil companies and speak to the tech department, and they say the mechanic is ignorant and not up to date with how oil works. He is just going of what worked 30 years ago.

A 0w 40 weight oil is heavier/thicker than a 5w 30 or even a 15w 30. So to need a 'thick oil' to stop oil leaks, a 15w 30 would of actually been thinner and counterproductive.

The 0 weight means the engine will be better protected at start up as 0w is thinner than the 5w and much more so than 15w. Also important to understand when you turn your engine on it is cold, so it will run off that first number, the sooner that oil gets through your engine the less wear it will take as a lot of an engines wear happens during cold start up because parts start moving without being properly lubricated. If you think about it in an extreme example, its metal on metal at start up before the oil gets through, so the sooner the oil gets through the less wear you get prolonging the engines life. So a 0w will always be better than a 5w and much much better than a 15w. Wherever a service manual is called for a 5w or a 10w or even a 15w... the lower you can get (0w in this case) the better as mentioned already, the oil gets to your parts sooner to prevent the wear happening on cold start ups.

This is why you should not use a 20w if the service manual calls for a 15w. Trying to push that weight through the engine on cold start up, you are asking for premature wear. So having a higher W number is not recommended but lower than what is called for can only be better not worse.

The last number in this case 30 or 40 is the viscosity of the oil at running temperature.

Important to note that 30 or 40 does not mean thicker than 0w at start up. That does not designate the thickness. Any oil (cook with oil etc) once oil is heated up it will be thinner than what was in the bottle. Same with the engine oil, it may be a 0w 40, but the 40 is operating temperature and therefor thinner than the initial 0 (when its sitting in the bottle it is in its thickest state). However, 40 at that thin operating temp will be thicker than the 30 in the 5w 30 at operating temperature.

In hot climate, a 30 or 40 weight (top end, operating temperature) shouldn't be too thick for application (like say a 50 or more which can cause lowered economy in tight tolerance vehicles)

So I would personally use the 0w 40 over the 5w 30.

Better protection at start up as it is thinner and gets to the engine parts sooner when most of the wear happens on your vehicle, and slightly thicker oil at running temperature when the engine is working hard, thus keeping it more protected there than the thinner 30.

Also worth noting most of the companies technology/research seems to go into the newly developed 0w 40 weight oils so the additives and everything else in the oil will probably be better as well as the base stocks being better over the other weight oils. The reason I mention that (which was mentioned to me by mobil and castrol oil companies) is because I was looking for a 50 weight oil thinking that a 50 weight will protect even more at higher temp than a 40 for regular use, but the 0-50 or 10-50 whatever they were (dont remember) were not as good as the 0w 40 versions because more of their research goes into the 0w 40 (more people need 0w 40 than a 50) so though it was 'thicker' its all the stuff/technology that goes into that oil that is not as good as the 0w 40.

So unless you need the thickness of a 50 oil, the 0w 40 will protect your engine better (going of what castrol said to me) is that the engines oil protecting ability lies in all the stuff that is in the oil. If it was just oil that protected the engine, then you could just stick vegetable oil in your car and be done with it.

So an oils ability to protect, clean etc the engine is based on how much of the stuff (additives etc) are left in the engine. The longer you go between oil changes, the more of that stuff is used up;. That is why oil changes need to happen, not because theres no oil in the car but because all the stuff in the oil designed to protect, clean, coat, etc the engine have been used up and no longer in the oil. The oil is essentially just a medium for those things to work effectively.

So those things (additives and stuff) are better in 0w 40 weight oils as that is where most of their research goes.

If you plan on selling the car like most people, then I doubt it will matter to you personally what you use. But if you want to have the insurance policy for your peace of mind, get the 0w 40 not the 5w 30 it is the better oil and will protect better at cold starts and operating temp. From memory I'm pretty sure they told me the 0w 40 will also last longer between oil changes because it has more of the additives etc in the oil. That is why there just is no logic in changing an oil early, only change it when the additives designed to clean/protect etc the engine are starting to get low, not before, and generally the 0w 40 has more of them than the 5w 30 and thus the oil change intervals are longer (more stuff in oil to do the job longer).
 
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