Question: What REALLY matters for a motor oil?

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What's considered reasonable? Wouldn't this depend on a lot of factors?

A very good point. I don't over think it every 5 to 7 thousand miles or 6 months generally seem to have worked very well. Better oil and better filter than the oil store and costs less. But with the Virus and such my mileage has dropped off considerably so it looks like I put my October change off. I only have a little over 1500 miles on this OCI. Looking like a March or April change now!
 
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A number of things really matter otherwise you wouldn't need spider graphs to display it all. Testing sequences are multi-variable for a reason. But in terms of consumers picking an appropriate oil I'd argue it is pretty simple. What matters most is that you follow good maintenance practices and not focus so much on just a single variable (the brand of oil).
 
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I would change that to "Maintains minimum HTHS required by engine design". Manufacturers are likely well aware that most GF-5/GF-6 5W-30 is simply 5W-20 with a lot of extra VII.

0W40 or 5W40 oils have lots of vii I assume.
should we call 5W40 a simply 5W20 with "a lot of extra VII"? :unsure:
 
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Muncie, Indiana
0W40 or 5W40 oils have lots of vii I assume.
should we call 5W40 a simply 5W20 with "a lot of extra VII"? :unsure:
Not necessarily most of the Eurocar 0w40 oils seem to be loaded with GTL and PAO that have naturally high VI and have high shear stability, where as something like Delo 400 5w40 or Rotella T6 are probably hydrocracked crude loaded with VIIs and are known to shear.
 
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4,710
What matters to most in the real world is that they dont have to lift the hood. The oil change light tells them its time..


So many %- dealer oil changes only.
So many %- whatever the oil change place puts in.
So many % - whatever the oil filler cap says.

Then there are the guys on this forum. Some use 15w40 in a Prius, some use 0w20 for towing.

If that 0W-20 maintains its HTHS then it might he very good oil for towing..
 

OVERKILL

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Ontario, Canada
I wish the SAE would test motor oil at 3,000 and 5,000 miles and see which oil still meets their standards.Now that would be interesting.

You realize many of the testing protocols for even the basic API approval have a time duration component to them, right?

For example, Seq IVA has a 100 hour duration, which, if your average speed was 30mph, would be the equivalent of 3,000 miles.

IIIF is 80 hours
IIIG is 100 hours
VG is 216 hours
VID is 100 hours
 
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Decatur AL USA
0W40 or 5W40 oils have lots of vii I assume.
should we call 5W40 a simply 5W20 with "a lot of extra VII"? :unsure:

A 0W-40 is usually uses bases similar to an A3 0W-30 and a 5W-40 bases similar to an A3 5W-30 so yes I would. Why do you think we often see 0W-40 drop into the 30 Grade range on short drain intervals? This also why many Euro manufacturers treat these grades as interchangeable as long as A3.

An HDEO 5W-40 may be an entirely different thing but I assume we are talking PCMO.
 

OVERKILL

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A 0W-40 is usually uses bases similar to an A3 0W-30 and a 5W-40 bases similar to an A3 5W-30 so yes I would. Why do you think we often see 0W-40 drop into the 30 Grade range on short drain intervals? This also why many Euro manufacturers treat these grades as interchangeable as long as A3.

An HDEO 5W-40 may be an entirely different thing but I assume we are talking PCMO.

As discussed in the other thread, most viscosity loss is from fuel dilution, not shear.

On the topic of blending:
Things being relatively equal, a 5w-40 will have less VII than a 0w-40, per this example but you can see the base oil blend is different:
Screen Shot 2019-02-04 at 11.31.11 PM.png


but all things are rarely equal. Here are some more examples specific to the 0w-30/0w-40 thing where the base oil blend is different:
Screen Shot 2019-02-04 at 11.31.42 PM.png

Screen Shot 2019-02-04 at 11.32.07 PM.png


And then here's a "typical" full synthetic PAO-based PCMO 5w-30 (unicorn) which has basically the same VII content as the first PAO 0w-40:
Screen Shot 2019-02-02 at 6.01.56 PM.png

Yet here's another, along with a 5w-40 that have significantly less VII:
Screen Shot 2018-05-07 at 6.13.53 PM.png


Now, leaving XOM and their pimping of PAO, here we have a Group III 5w-40 example from SK that has more VII than all the examples above:
Screen Shot 2020-09-28 at 9.02.58 AM.png


So really, there's no hard-fast rule of thumb as to VII/VM content. Oils are all blended to a price point and blenders will typically use the cheapest bases they can to meet the target. This is why there's so much more PAO in Mobil's 0w-xx oils than in their 5w-xx ones for example, why Castrol 5w-40 is entirely group III whilst the 0w-40 has half the base oil blend as PAO, which, as you can see from the two Mobil examples, allows a relatively low VM treat rate when compared to an all Group III 5w-40 like the SK example.
 
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WA
A 0W-40 is usually uses bases similar to an A3 0W-30 and a 5W-40 bases similar to an A3 5W-30 so yes I would. Why do you think we often see 0W-40 drop into the 30 Grade range on short drain intervals? This also why many Euro manufacturers treat these grades as interchangeable as long as A3.

An HDEO 5W-40 may be an entirely different thing but I assume we are talking PCMO.

you said manufacturers are aware that some 5W-30's are simply 5W-20's with a lot of extra vii ... or something to that effect.

Technically speaking, 5W30 is a 5W30 so I was just pulling your leg :)

anyways, it made for some good discussion and additional technical info by @OVERKILL
 
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