5w-30 versus 0w-40?

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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.)
 
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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.)


Depends on how you are driving the car.
 
Meh, I doubt it would make much of a difference, and if there was I think itd be tough to measure. 5w30 does quite well, the higher specd 0w40 typically used in higher heat engines if im not mistaken. Personally, if OEM says 5w30 i wouldnt pay more for 0w40. Again its up to you. Either way, I doubt it makes much if any difference.
 
Originally Posted By: V8man
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.)


Depends on how you are driving the car.



Good point
 
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Even though the 0W-40 has a "0" for the cold SAE rating, it will likely still be thicker at the temperatures you care about, unless you live in northern Alaska.

This is even true of some 5W-30 / 0W-30 comparisons. For example, look at Mobil1:
"AFE" 0W-30 100C: 10.9 cSt; 40C: 62.9 cSt
5W-30 100C: 11.0 cSt; 40C: 61.7 cSt

Despite being thicker at 100C, the 5W-30 is thinner than the 0W-30 at 40C and temperatures below.
 
Eh, the KV values are not really that important. I would judge the oil's characteristics by MRV/CCS, VI, and HTHS.
 
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.
 
I would use it M1 0W-40 confidently!
- Long OCI.
- Extra protection while loading/hauling over reg 5w-30.
- Older engines usually like thicker oils.
- Weather like California should not impact your mileage much.
- If you have leaks or not a well maintained high mileage-engine, I would not recommend it then.
 
Originally Posted By: OceanRuns
So, assuming you're changing oil within 5-7.5k miles and 12-18 months, would the 0w-40 do better?

Not really. Sounds like you're more limited by time than miles in this scenario. And if that involves lots of short trips, I'm not convinced that a 0w-40 can handle it any better than a 5w-30 would.

Normally, an oil like 0w-40 would carry a bunch of stringent mfg LL specs (example: M1 0w-40), which would make it suitable for long drains, say 15-20K miles. But again, that's not your scenario, so I don't see the benefit. There are plenty of great 5w-30 oils out there.
 
Originally Posted By: V8man
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.)


Depends on how you are driving the car.


EXACTLY! If you plan on driving the vehicle, how the manufacturer expects it to be driven, a 5w-30 is perfectly fine. Heck, i would do a 0w-30 if your using synthetic.

Originally Posted By: NateDN10
Even though the 0W-40 has a "0" for the cold SAE rating, it will likely still be thicker at the temperatures you care about, unless you live in northern Alaska.

This is even true of some 5W-30 / 0W-30 comparisons. For example, look at Mobil1:
"AFE" 0W-30 100C: 10.9 cSt; 40C: 62.9 cSt
5W-30 100C: 11.0 cSt; 40C: 61.7 cSt

Despite being thicker at 100C, the 5W-30 is thinner than the 0W-30 at 40C and temperatures below.


Look at pour points. For extreme cold the 0w-30 would be better despite the viscosity index
 
If your question is more geared towards "would there be any harm in using a 0w40?" then no there would not. So if you want to go for it. an oil like M1 0w40 would work well for the OCI time you described.

The Major 0w's are not "propped up by additives" or VII's. Things have changed and these oils are blends of many different high quality base and top of the line additives. Use with confidence.
 
Originally Posted By: chubbs1


The Major 0w's are not "propped up by additives" or VII's. Things have changed and these oils are blends of many different high quality base and top of the line additives. Use with confidence.


Agree 100% that things have changed significantly in the zero-weight oil arena. I've been running 0W-30 synthetic in 5 vehicles for 1/2-dozen years and love the results!
laugh.gif
 
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Please excuse my bumping an old thread.

I've been running M1 0w40 for 3-4 years now in my 2003 Lexus IS300 with 59k miles. OCI is 12 months, ~6000 mi. The reason is that I stocked up each time pep boys had a sale for $5 per quart, and because I read somewhere here that the M1 0w40 is an excellent choice in cars that call for a 30 weight. And I also know that its viscosity is on the lower end of the 40 weight scale.

Is the conclusion I arrived at wrong? Assuming that we can ignore the cost, and ever so slight hit to my gas mileage (which is negligible in sunny San Diego, no?)? Put differently, is there a good reason to stop doing this, with the above caveats in mind?
 
Originally Posted By: rondoggnuts
Please excuse my bumping an old thread.

I've been running M1 0w40 for 3-4 years now in my 2003 Lexus IS300 with 59k miles. OCI is 12 months, ~6000 mi. The reason is that I stocked up each time pep boys had a sale for $5 per quart, and because I read somewhere here that the M1 0w40 is an excellent choice in cars that call for a 30 weight. And I also know that its viscosity is on the lower end of the 40 weight scale.

Is the conclusion I arrived at wrong? Assuming that we can ignore the cost, and ever so slight hit to my gas mileage (which is negligible in sunny San Diego, no?)? Put differently, is there a good reason to stop doing this, with the above caveats in mind?



E46 BMW 6 all use M1 0W40 here, or Castrol Edge 0W40 fwiw.
 
Originally Posted By: sprintman

E46 BMW 6 all use M1 0W40 here, or Castrol Edge 0W40 fwiw.


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?
 
Originally Posted By: rondoggnuts
Originally Posted By: sprintman

E46 BMW 6 all use M1 0W40 here, or Castrol Edge 0W40 fwiw.


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?


How can it be worse??
 
^Laymen say it all the time, for the simple fact that it doesn't match the specs of the engine. I've been told that it is unwise to deviate from the 5w30 called for, because the manufacturer spends millions+++ on researching it, so I should follow it without exception.
 
Originally Posted By: OceanRuns

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?


I wish I had made a note of where I read it so I could post a link, but I read an article that stated that this large viscosity range is no longer a big issue these days.

I read it in a rush but I seem to remember it was to do with use of better quality basesto is being used.

I wish I could expand further, will try to find it but I wouldn't hold my breath it was on one of those late night Internet trawls.

The two most common oils I use are 5w30 and 0w40.

Mobil 3000 X1 FE 5w30 in Pathfinder and V50 and now gone back to Mobil 1 New Life 0w40 in the Clio after 8k with Maxlife Diesel 10w40 synth blend.

Both do their jobs well.

In your example, as others have said.

Mobil 1 0w40 all the way.

I would watch out for a maybe an increase in oil consumption initially.
 
Originally Posted By: rondoggnuts
^Laymen say it all the time, for the simple fact that it doesn't match the specs of the engine. I've been told that it is unwise to deviate from the 5w30 called for, because the manufacturer spends millions+++ on researching it, so I should follow it without exception.
But we often read of the same vehicle/engine in other countries having different oil requirements.
 
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