What is the reason for monogrades?

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Cheaper for a given level of performance when hot, and less or no VII/PPD content.

AFAIK, some of them actually would test out as 15W or 10W, but they're labeled as monogrades for people who think they still need a monograde (e.g. they have an old OPE that specs it).
 
Originally Posted By: d00df00d

AFAIK, some of them actually would test out as 15W or 10W, but they're labeled as monogrades for people who think they still need a monograde (e.g. they have an old OPE that specs it).


Correct. Thats why I occasionally use monogrades without worry. In summer temps, they are absolutely excellent. Great for highway towing applications, too.
 
No VM junk in there. They might be multigrade capable but the lack of VM is important for some engine spec like Detroit diesel turbo-supercharged 2 stroke diesels bus engines. A robust 10w30 multigrade would likely lunch that beautiful engine whereas an SAE HD30 would not and assures stay in grade performance.
 
Originally Posted By: wemay
Thanks^

Is in inherently more stable, resistant to shear?

As a class, dollar-for-dollar, yes.
 
In marine and aircraft they are the norm, not multi-grades. Also in Detroit Diesels (2-stroke), they are absolutely mandatory. No viscosity modifiers and absolutely shear stable. All oil, all the time.

They show good upper ring band wear protection compared to multi's. There is absolutely no reason not to run a mono grade if you live in benign climate. Multi's were invented for northern USA/Canada and Europe where winter cold can be a problem.

So-Cal, AZ, TX, NM and most of Nevada can do w/o multi's completely. Same for FL and most southern states. No reason for multi's in Mexico or the Caribbean either.

But, refiners do not want to market lo-profit oils when they have spent big bux convincing most of the world of the superiority of multi's ...
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I just bought 8 gallons of SAE 40 SN for $10.00 on sale at TSC. Nobody is making any money at that price ...
 
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Depends on where the equipment is operated. In Nebraska in winter, even construction equipment gets multi's, or block heaters, etc ...
 
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Originally Posted By: BrocLuno
Depends on where the equipment is operated. In Nebraska in winter, even construction equipment gets multi's, or block heaters, etc ...


Your right. Used in summer only, like using 30 weight in lawn equipment etc.
 
Monogrades also work very well in shared sump motorcycles where the engine oil also lubricates the transmission, gear shifting mechanism, and the clutch. In other words, everything. The gears really do a number on the VII's in multigrades. Monogrades are immune.

On a car, you don't really feel the effects of oil that has sheared down. On a shared sump bike, you do - shift quality goes downhill and results in poor shifting and even missed shifts.
 
Naturally, monogrades existed first.

The different oils from different regions had different properties, some showed less viscosity change with temperature and were considered more desirable. So they were given a "viscosity index" of 100 (the best), and the worst given zero.

Synthetics had viscosity indices higher than 100 and were more desirable.

At some stage, viscosity index improvers were developed, and "multigrades' came about, that could cross the boundaries between a thin and thick oil...or add a lower "W" rating for a given KV100 basically.

These were ultimately found to no offer what they promised, and high shear viscometry was born.

Monogrades do not change viscometrically with the rate that the wear surfaces move past each other ... they are "Newtoian"...multis don't do that, they change with shear rate as the polymers "flatten out"...here's one of the early tests...


One of the "50s" perfomed as well as a 40, the other about as well as a 30.

That's why HTHS minimums were introduced into J300 (which has evolved continuously since the 20s), as it was found that HTHS was more related to bearing wear. (Ealy on, the 0W, 5W, 10W 40s were only required to have a 2.9 min, just like the 30s...that was changed recently to 3.5)...note, a mono 30 has an HTHS of about 3.5+
 
As I've mentioned in other threads, the new sawth of 0W16 and 0W8 oils are going to very closely resemble mono-grades with low PPD, VII and VM additives. This is because they already pass the cold pour tests as they're so thin to begin with. As has been mentioned in this thread already, mono-grades are much more sheer stable over the life of the oil. It also means that you don't need to spend as much on your additive package. But rest assured they will not pass those savings onto the consumer
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Jordan
 
There are climates where they make sense and there are engines like OPE and DDA two strokes that call for them.
They also make sense as add oil because they have no VIIs which may behave in an unpredictable manner with any given sump fill.
SAE 30 is among the grades recommended in the OM of our '09 Forester, so I could use it in that during the summer months.
I bought a case of SAE 30 to use as add oil a couple of years ago for $1.29/qt.
I've still got eight quarts left, but they'll eventually get used.
 
There you go. A good summer time oil is very cool. I ran a straight 30 grade this summer in the Camry. It ran much better on this versus the Pinnacle 5w30 I tried in it. That stuff ran very loud in there. It was summarily replaced really quickly with Valvoline Maxlife full synthetic.
 
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