Motor oil article

no.

it means the thirty weight oil is superior from day one, the day you pour it in, until the day you drain it out, and all the days in between.

 

Agreed. In particular shear can be a factor with tight tolerances.

One of the things I like about synthetic in Prius engines is that synthetic seems to have better film properties compared to dino oil. With many more starts I want that.

The original article failed to deliver in many ways. First, it implied things without ever providing any hard data. Second, its opening lines clearly identified it as an opinion piece. ("The purpose of this article is to challenge conventional wisdom" and "the American consumer does not appear to care too much about fuel economy.") That precluded doing a full read, but scanning through it I'm not seeing any meat to back up the initial claims, just vague theory.

 

Nice Article Thanks
So what is a good oil for a gen 3 Prius 2010 about 84 k mile slow acceleration driven speed limit or under in California?

 

My pick is 0W20.

 

My pick is 5w20, 5w is good for 7F degree or higher so it has more thickness for startup protection. 0w will be too thin for start up for warm non snowing climate.

 

A 0wt at startup temps is still way thicker then the 20wt at operating temp? This comment makes no sense to me.

 

Actually much of the wear occurs at start up, before the oil is sent to all the contact surfaces. In this sense, the lighter the oil (smaller number before the letter W), the easier it is being pumped from the crankcase to the contact surfaces. I hesitate to write this out because it is too technical, leading to pointless argument.

 

Not necessarily. To earn that w rating an oil just has to clear a maximum thickness at the specified temp and the manufacturer can slap whatever lable they want if it clears that hurdle. It's possible for a 5w oil to be thinner then a 0w oil for example.

Amsoil used to have a 15W-40 synthetic that could have been labeled as a 5w. The oil met the requirements to be called a 5w, but marketing demanded it stay a 15w-40 because a lot of truckers thought a 5w was too "thin".

 

That qualifies for your list of foolish quotations.

 

I guess it is possible. So I should take off the words in the parenthesis (smaller number before the letter W).

That is like Toyota markets their 50 MPG Prius as 40 MPG.

Could you please provide the source of this Amsoil 15W/5W story? This becomes very interesting...

 

Imho, pure InterWeb BS.
There are very specific certification procedures and specifications.
Manufactures do not get to pick specs and certs from their rear-end.
I've been involved in too many industry certification tests, to remember. When a product fails to meet any test specifiction, is when some PhD's earn their money. Iirc, for oil, it's not hard/very-expensive to do 100% accurate preliminary testing, in house.
For some things like EMI (electrical noise) emitted from electronics, the 100% proper setup is very expensive, and single purpose in use.

Check out Project Farms tests of different oils (on youtube).
Fwiw, it depends on what startup temp is being used. In the hottest day in Saudi Arabia, the startup temp is already near operating temperature.
At 2am, in mid February in Northern Maine, (in honor of Halloween) it's colder than a witch's *********.
Therefore, 0W oil(at ~-10F) flows rather slow. Kinda like Maple Syrup.
However, once the engine is at ~190F(operating temperature), 20W oil(at ~195F) flows similar to Olive Oil.

 

That is a very common misconception. An ideal motor oil would have the same viscosity at all temperatures, but in reality, all motor oils are always too thick (thicker than optimum) during startup and warmup.

For example, a typical 10W-30 oil might be ten times thicker at room temperature than when fully warmed up, while a typical 5W-30 oil might be only nine times thicker at room temperature than when fully warmed up, and they both have the same optimum viscosity when fully warmed up.

This is at least partly true. When comparing motor oil specs, I once found a 5W-30 oil which was slightly thinner at 40°C than a 0W-30. Sometimes it depends on the specific formulation of specific oils.

 

To compare 5W with 0W, one needs to check their viscosity at winter temperature (per SAE classifications), much lower than 40C.

Majority people start their cars at a temperature lower than 40C most of the time any way.

Nevertheless, could you please share the data/source of your 40C comparison. It is interesting to me.

 

Manufacturers don't get to pull things out their nice person, but SAE J300 gives a lot of leeway when it comes to w ratings.

For the W rating a maximum viscosity at a specified temp is what is required to be considered for that rating. The grades for operating temp, like 20wt, 30wt, 40wt etc....have to meet many more criteria. They have to be within a certain range at 100C and meet HT/HS numbers among numerous other things.

A 5w oil has to under 6600cP at -30. A 15W under 7000cP at -20. Amsoil's has a 0W-40, a 5W-40 and 15W-40 diesel oil now. Their spec sheet lists 0W-40 at 5776 (-35), 5W-40 at 5555 (-30) and 15W-40 at 4134 (-20). It's not listed specifically, but it's not unreasonable that their 15W-40 full synthetic would be under the maximum 6600 at -30 given the specs given for their 5W-40 at that temp and considering the viscosity at both 40C and 100C is similar and the 15W-40 has a low viscosity index. Conventional oils have to meet that 5W spec, so it's hardly crazy that a PAO/POE based oil wouldn't be able to meet that while also being able to meet the 15W spec. If the oil meets the criteria, it's up to them to label it how they see fit. Afterall, it met and exceeded the requirements so their is no mis-leading the consumer. It's better then required.

For comparison, conventional Castrol GTX lists as 5600 at minus 30. Amsoil 5W-30 at 3968. It might seem crazy, but when you start really diving into tribology, the devil is in the details.

Yeah, it's gonna matter what's in your engine at 2am in winter in Maine vs anytime in Saudi Arabia, for a cold start, but that is a separate issue from what is on the label and how that label is determined. Perfect example of how one size does not fit all.

As for sources, simply Google SAE J300 and you can find specs for Amsoil and Castrol on their respective websites.

 

Perhaps this is like the "new math".
But isn't 0 less than 30?

The whole idea of multi viscosity oil is so while the engine is cold, the oil is thinner
and flows easier, because that's when most of the wear comes from, because the oil
has drained from the bearing surfaces. Then it becomes thicker as it heats up so the
bearing surface are protected.
If it was 30w all the time, while it's cold, it would not flow easily and the bearings would wear.

 

Two different ratings though. It's not as linear as it might seem.

Its impossible for the same oil to be labeled as xW-30 and xW-40, but not impossible for the exact same oil to be labeled as 0W30 or 5W30.

 

Specs Mobil 1 ESP X1 0W-30 by Fred_H posted Nov 2, 2022 at 1:45 AM

Specs Mobil 1 Extended Performance by Fred_H posted Nov 2, 2022 at 1:46 AM

 

Thank you.

 

Actually, it is the opposite: old math.

A long time ago, there were only single grade motor oils, such as SAE 10W, 20W, 30, 40, 50. People who lived in climates with large temperature changes between summer and winter changed their oil at least twice a year. In summer they used a thicker oil grade, and in winter they used a thinner winter grade with the suffix "W".

If a summer oil was used in winter, then on cold days the engine would not start, because the oil was so thick that the starter could not crank the engine fast enough to get it running. If a winter oil was used in summer, then on hot days the engine might seize, because the oil was too thin to provide adequate lubrication.

The winter grade oils were still much thicker than ideal at low temperatures, but thin enough to start the engine. The summer grade oils were thinner than ideal at very high temperatures, but thick enough to prevent engine failure.

Then oils came along that didn't change viscosity quite so much with changing temperatures. Using the old nomenclature, they were described as being as thin as an SAE 20W grade oil at low temperatures, for example, but as thick as an SAE 40 grade oil at high temperatures, for example. This description could be shortened to SAE 20W-40, for example. So came about the current nomenclature of so called "multi grade" motor oils based upon the old nomenclature. They are oils that fulfill the requirements of two (or more) different single grade oils. Old math.


Even the very best modern multigrade motor oils still become much thicker at low temperatures, but only so much less so, that it is now seldom necessary to change oil grades with the seasons.

 

?????? That's what I was pointing too. 0=thinner, easier flow when colder, 30=thicker when hotter
so engine won't seize....