2012 Prius C 10k mile oil analysys

Thanks for the correction, I had my brain on backwards.

So, just a curiosity then? I still can't find a good reason to go thicker.

 

Back in the olden daze, the wider the viscosity spread on multi-viscosity oils, the sooner the oil sheared and broke down so if a person still has their grandfathers mindset, 5W-20 would be a considerably more durable oil than 0W-20. However, if you are using a decent quality synthetic oil, their is little difference now.

If you are doing track days in a warm climate, then the higher viscosity might be worthwhile

 

Well, I've got a few grand kids, so...

Go back a few decades and no one had heard of, or would even consider, an oil as thin as 5W20. The norms were 10W30, 10W40, even 20W50.

I'm not knowledable as to what's caused the shift to thinner emulsions. The main motivator's likely to improve fuel economy. I've read that closer/stricter tolerances allow the thinner oils to work. That thicker oil might actually be problematic with close tolerances. And maybe it's just a shift in mindset: engineers trying the thinner oils, seeing how they fare.

This is from 1990 Honda Accord Shop Manual:

 

I've mentioned this elsewhere, but for what it's worth, our manual has a diagram that shows operational ranges for 0W-20, 5W-20, 5W-30, 10W-30, 15W-30 and 20W-50, with the accompanying text:

Clearly this is different from the US manual which is fairly emphatic about using 0W-20 and only grudgingly offers "If SAE 0W-20 is not available, SAE 5W-20 oil may be used. However, it must be replaced with SAE 0W-20 at the next oil change."

Who knows what Toyota's thinking is behind this, although the fact that Australia has minimum temperatures around 0°F and my c is unlikely to ever see anything as low as 20°F (like most c's here) does indicate our climate is very different from minima in the US.

 

For Toyota to be able to claim their mileage rating under US regulations, Toyota has to push the oil the car's fuel economy rating was based on. That is the main reason Toyota US pushes 0W-20 only.

I suspect there is also a second reason that they are very specific about 0W-20 instead of 5W-20 in the US. Toyota wants to be able to claim a 10k mile oil change interval in the US and with US quality of oils, that requires a synthetic oil. At least when I got my Gen III, Toyota seemed reluctant to require a synthetic, but by requiring a 0W-20 they eliminate almost all non-synthetics.

 

In the American market, Toyota cannot specify a synthetic oil only. In the EU, they can follow what other companies, such as Mercedes, VW, Audi, etc do and specify a unique oil that meets tight specifications.

There is no distinction in the North American market for better oils. No matter the cheapest no-name, or an expensive synthetic, they will have an API SN and GF5.

http://www.api.org/certifications/engineoil/categories/upload/motor_oil_guide_2010_120210.pdf

The European ACEA rated oils have distinctive ratings based on normal or severe service, normal or extended oil drain intervals. The ACEA oils meet different specifications, and the manufacturer is free to set their own specification too

It should stand to reason a no-name oil will NOT be as good as a synthetic oil. But under the API, all oils are graded the same. So the consumer will make the wrong assumption that all oils are exactly the same.

 

There is nothing that limits US car manufacturers or imp0rters of cars to the mediocre API specs.

If Toyota doesn't understand that, they need to go to GM, Porsche or some other car companies that use tighter specs that only a synthetic can meet for some of their cars. And no, the mythical properties of the widely misunderstood Magnuson Moss act don't disallow that as long as the oil is available from sources other than the car company.

 

The problem is that in North America, the API only has the one grading system I pointed out. This results in a great deal of confusion, as the average motorist has been led to believe that all motor oils are exactly the same, and perform exactly the same, because they only have one grade. Such as GF-5 or SN

My wife has a 2012 Impala that requires Dexos. We understand this oil is necessary, especially for gasoline direct injection. But the average Chevy owner does not. When I had the Impala in for its first complementary oil change, another Chevy owner refused to pay the extra cost of Dexos. Said he would get whatever cheap oil is on sale and do it himself, as "all oils are the same."

As far as Dexos, you're pretty much forced to use a synthetic like Mobil 1, Castrol Syntec, etc. I'm ok with that, but evidently a lot of Chevy owners are not. They had better not complain when they have trouble with deposits in their gasoline direct injection, or timing chain stretch, or other issues if they use a cheap bargain oil

 

Garbage in, garbage out. American's [as a well-deserved stereotype] are rather ignorant to this concept, instead relying on the hugely popular "frivolous lawsuit in, any sort of responsibly out".

 

I really hate to agree with that comment, but I do agree

 

I would like to add that although I can and usually WILL use a somewhat heavier oil in hot conditions, in severe cold I will run the lightest oil I can. Such as a 0W-30 or 0W-20.

This gem is from the early 1990's and showcases Esso Canada's heavy duty engine oil lineup, the XD-3 series. They use a car in their cold weather room at -35 C to prove a point of using their 0W-30 versus their 10W-30. Note that both are heavy duty oils

Skip ahead to about 4:20

That poor car. With a battery booster and continuous cranking, it took over a minute of cranking with the 10W-30. I have heard starters grind like that, but usually just before they fry

 

Wait I am confused about something-
There is a lot of talk about full marks and filling to the full marks here, however, when you put engine oil into the engine it is COLD. When engine oil heats up it expands. When engine oil at the full mark expands it goes above the full mark.

So isnt it pretty stupid to fill to the full mark if your intent is to not ovrfill the engine?
Also if the oil is a few mms below the full mark (when cold) it does not mean the engine is running on empty. They give you a range where the engine would have a safe amount of oil taking into account temp changes.

 

Like any tolerance spec, I'd think midway between the two marks on the dipstick is the sweetspot, if the engine's not consuming oil. In reality most engines do consume a little oil between changes, so leaning towards the high mark is a good strategy. And slight overfill is not going to catastrophic: any oil level has surely been set by the engineers with a goof-up factor.

FWIW, our 2010 Prius doesn't appear to consume any oil, over the 6 month change interval I've been following (Canadian spec). That's a first for me, coming from a string of Hondas.

 

Bingo. Oil expands about 1% for each 100C increase in temperature, so from 0C (freezing) to 100C ( a reasonable oil temperature for a warmed up engine), 4 US quarts of oil will expand approximately 4 x 0.01=0.04 US quarts which is 2.6 US Tbs. Start from a more reasonable 20C and the expansion would be 2.0 Tbs.

 

As far as work escapades, unfortunately I can't use the excuse of being under the influence of anything. I'm pretty sure I was born this way