Another Oil Question

It's more efficient.

It also allows for less frequent changes. Every 10,000 miles.

As for protection, the hybrid system alone does a far better job than traditional designs anyway. No need for more beyond that.
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Some 'hidden' agendas:

0w20 is only made in a synthetic oil. So in effect Toyota is saying use a synthetic oil. Dealers using some other weight are trying to avoid synthetic as too pricey. As an owner, you pay dealer prices for oil that Toyota will not support their warranty with. Not good.

Some of this is liability oriented. Toyota changed to 5000 mile oil changes due to sludge damage and the resulting lawsuits. With synthetics, Toyota can return to 10,000 mile OCI, with no fear of sludge, but how do you force the owner/dealer to actually buy synthetics? Picks a weight that only comes in synthetic.

Making cars with great EPA numbers allows you to also sell cars that people actually want to own, and still keep the total fleet numbers under Mileage limits, avoiding gas guzzler fines. Lightweight oils help with those EPA numbers.

I wish I could tell you it was engineers, not lawyers, choosing the weight of your oil, but that is the society we live in. "The first thing we do, let's kill all the lawyers" is not a recent idea, but it seems more and more reasonable as we get more and more lawyers.

 

I've always been torn on the question of viscosity vs apparent wear protection. Generally, motor oils sold in the EU are "thick" compared those sold here, as they have to provide protection at autoroute speeds and also extended oil changes approaching two YEARS

Consider the made in Germany Castrol Syntec 0W-30. It tests out as a solid 30 oil, whereas in contrast most 5W-30 oils sold here test out near the bottom end of what is considered a 30 oil

In bitter cold temps, thinner is ALWAYS better. There is a lot more wear at startups <20 F and colder, and if too thick an oil is used the oil pump drive can actually shear off

Hot temps, I'm not so sure anymore. There are plenty of Ford's, Mazda's, and Honda's cruising around Arizona, Nevada, and SoCal with 5W-20 their entire life, with no apparent impact on engine life

I let the used oil analysis be the deciding factor. I ran a non-approved viscosity in my 2004 Prius, Mobil 1 0W-20. Had excellent results even up to 10,000 mile oil change intervals

My FJ is approved for xW-20 oils, and I did NOT have good results running this viscosity. The biggest problem was nitration, and in the case of Mobil 1 0W-20 it actually thickened up to a 30 range

In the end, YMMV. I have never seen a 5W-20 sold outside of the US or Canada, which alone tells me something

 

It is purely for competition. Because other manufactures have started to use them to get better MPG so they want to follow the bandwagon.

The longer service interval is also the same reason because others are going for longer service intervals so it is "supposedly" cheaper to run to entice custumers to buy their cars for cheaper maintaince.

But can the oil and the engin actually go on that long a milage before service? Well a lot of them can't and shouldn't and they themselves knows that but due to competition and pressure they push it as far as they can.

If you ever have any relatives work in a dealership you will know how crafty and crap they are. Personally I don't trust any of them.

Cut to the topic, I think that if you live in a cold area you definitly want the 0W part because that shows that the oil is still good at low temperatures.
I would recommend 0W30 although I am using 0W20 myself at the moment but I feel the 0W20 is a bit thin but I will have to stick with it for a while since I bought a lot of the oil for this car.

But if I am going to buy oil now I would buy 0w-30 because it covers a much bigger tempreature range compared to 5w and 10ws and also it is thicker than 20s, which should give better protection but lose a bit of the MPG.

 

With my Prius, the only time I noticed a difference between 0W-30 and 0W-20 was in winter, and the temps had to be <-25 F. Then, perhaps 3 mpg more

But in summer, I had fuel economy that was statistically similar, running 0W-30 or 0W-20. As I had good lab reports from the 0W-20, I chose to run one oil year round

With the FJ, no difference whatsoever running 0W-20, 0W-30, or 0W-40 at any temp. The 0W-40 provided the best lab reports

 

Real data for Mobil 1 in an extended change interval test.

Mobil 1 Test Results

The results are consistent with what the motor companies have observed and what the oil companies have also seen--but, may not necessarily advertise.

 

I am now thoroughly confused after this varied assortment of information on what viscosity to use in this rather mild climate (Dallas, TX, where temps rarely go below 20F in the winter and can reach heights of 110F in the summer).

 

It seems most of you here tend to think or agree that using synthetic oil can prolong the oil change frequency. I'm not too sure about this because most car magazines and shows are saying we should stick to the factory specifieed intervals even if synthetic oil is being use. The reason, as explained, is because oil do get dirty along with the internal combusion process. Carbon and dust, etc. all got mixed up with the oil with time. Assuming this is true, then we should still change the oil according to what the car manufacturer requires us to follow. Therefore, the only benefit from using the synthetic is to reducing the start up wear and tear on the engine, especially in cold weather regions. If you live in areas like Dallas, you shouldn't worry about cold start damage but on high temperature engine protection. Thus using even 10w30 or 10w40 is appropriate.
Again, I'm not 100% if my theory is correct. Please correct me if I am not.
BTW, Canada Prius still requires oil change interval at 8000km/5000miles. There is no words that Canada will follow US to extend the interval even though 0w20 is the specified grade.

 

I've got 8,000 miles on my 0W-20 now. Checked the dipstick this morning and was pleased to see it still hadn't darkened to want I'm used to seeing at just 5,000 miles on my mother's Corolla.

Prius is remarkably easy on the engine, especially with startup. The wear traditional vehicles see is significantly more than we see in Prius. It has a far better start method.

Heck, even with the factory 7,500 on the Classic model with 5W-30 we were thrilled with how the oil still hadn't thicken as much as you'd expect at change time. So, with the 0W-20, it's no big deal. The bigger engine doesn't have to work as hard, especially with the more powerful electric motor.
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Near as we can tell, the 1.5L engine does not respond well to overfill and the 250k mile Prius was reported as having oil consumption. The stored codes and observed O{2} sensors indicated the catalytic converter was probably bad. We can't rule out bad O{2} sensors but in this case, it makes sense. But we know overfilled oil leads to a puddle in the intake manifold and when combined with high power settings, probably oil loss out the exhaust ... not the best thing for the catalytic converter.

As for engine oil, I tend not to get too worried about it. I change it twice a year, late Spring and Fall, and it is not really a problem. A Prius engine has an easy life, MG2 does a lot of the heavy lifting. The Atkinson cycle means it is worst case, running about 75% of the equivalent Otto cycle version. Then there are the gentle footed Prius owners. So all in all, the ICE has a happy and should be long life.

One subtle, new-car feature of the 1.8L engine is an improved "Blowby Gas Ventilation System" that includes an oil separator baffle. Part of the PVC gas path, it minimizes the amount of oil lost through the PVC valve and into the intake charge. This should mitigate some overfill, engine oil problems.

I do pay attention to the transmission oil because all power has to flow through that area. After throwing away 2/3ds of the chemical energy to make shaft power, it is poor judgement to tolerate any avoidable friction loss down stream in the transmission, wheel alignment, or tires.

So I changed my transmission oil at 5k miles and sent it off for analysis. It showed some shear down and evidence of wear material. I was happy to get it out and will drain and test it again at 20k miles. I'll use these results to determine the next oil change interval. We've just passed 10k miles so there is another 11 months to go.

Bob Wilson