Whats the factor to watch at really for motor oil?

[Japoc]

Hello,

i have a Toyota Prius Hybrid from 2010. The manual says allowed are 0W20 till 10W40 but 0W20 should be used. 5W30 can be used but only if needed and next time 0W20 should be used again.
Change interval is 15000 km or 1 year. I live in germany and i practically only drive short tracks. Under 5 kilometers, stop and go through the city, and im driving conservative to not having a high gasoline usage.
My car has no problems except after the last checkup.

When i got my car back from checkup i was wondering... i constantly had one liter more gasoline usage. With my short tracks i wasnt near the numbers a prius should have anyway... though i could go near that numbers after driving long ranges and resetting the timer when the motor is warm. Though only with short tracks, where the motor doesnt get warm really, its probably not possible to get the lowest consumption.

Anyway... after checkup i had one liter more. And its constant. I checked the receipt and the manual and found that Toyota wants 0W20 to be used. The workshop added 5W30. So im pretty confident the problem can be found in there. Nothing else was changed except the checkup, new air filter and spark plugs.

The workshop boss didnt want to change the oil afterwards, only offered to give me 0W20 the next time for free. He didnt believe my numbers for gasoline usage but the numbers are consistent.

So im at the point to change the oil to 0W20 on my own. Because when i have to pay for 1l gasoline more each 100km then it would be pricy at the end of one year. So i have read a lot about oil now.

Mobil 1 isnt very good with viscosity? Its pretty often used as an alternative in my country because the toyota workshops dont have 0W20 mostly. But now i found someone claimed its 35% heavier at 0°C and 25% heavier at room temperature than TGMO. I checked Royal Purple and its viscosity index sounds similar to the one of Mobil 1 too.

Then i found there are 0W10/5 from royal purple too. But i have read in the forum that the viscosity isnt as good as TGMO 0W20 even with the better numbers. I dont see why these oils can wear better numbers when they arent as good at the end.

So whats correct now? Whats the numbers i should watch at when chosing the oil? Like i wrote... im having a hybrid. The hybrid gasoline motor barely gets warm anyway and mine the more because of the short tracks i drive only. Seldom i drive freeways but it happens too occassionally.

So searching for the highest viscosity index? Somehow finding out the best viscosity at 0°C and around the temperatures in my area? I dont really know what to look for now anymore.

Of course i dont want to crash my motor. Only want to drive with the least gasoline usage.

Is there a table with most oils to check out details like VI and other values fast? I didnt find anything like that though such thing should be known in this forum when it exists.

Thanks!

 

[Donald]

I am thinking you will get condensation and fuel and will not get the engine hot enough to burn either off. If thats the case then just use PYB in the proper grade and change it more often.

 

[BertieBlue]

I think your viscosity is causing the extra L/100m. I would image the engine works harder with 0-30 than 0w-20, especially so at the less than full op temps the Prius can run at.

Order 0/20 online and when it arrives change it.

In the case of the Prius, viscosity is very important.

 

[InhalingBullets]

The only time I ever saw a mileage decrease in the Prius was when the 12 volt battery was going out. Regardless of whether we used 0w/20 or 5w/30 we always got 48mpg average.

 

[TrevorS]

Donald, the OP is in Germany!

Japoc, welcome to BITOG.

I can understand your confusion. Very simply there are two elements affecting your fuel economy.

1) Oil viscosity
2) Viscosity Index

You are right that 5w30 reduces fuel economy compared to 0w20. Ford estimated 0.6%. On top of that, within the 30 weight, some oils can be lighter and some can be heavier. In Europe in particular, many 30 weights are at the heavier end of the scale.

Now remember that this viscosity is at operating temperature as measured by HTHSv or if it is not available V100c.

30 weight oils can have HTHS of 3.0 to in excess of 3.5.

Compare that to 20 weight oils that are typically 2.6-2.7 but can be as high as 2.9.

So you get an idea that a 30 weight at operating temp can be significantly heavier than another 30 weight or 20 weight oil thus affecting fuel economy.

However, 20 weight oils at operating temp are generally in a narrow range of viscosity, usually 2.6-2.7.

In general, a thicker oil at operating temp is going to be thicker at start up temp but some oils are better at this than others, and this is where viscosity index comes in.

The manufacturer branded (Toyota, Mazda, Honda) 0w20 oils have the same operating temp viscosity as most other 20 weight oils, but they have significantly better viscosity at start up temps.

These viscosity indexes are in the 220 range vs 160 for regular 20 weight oils. This is why you hear on this forum, (from Caterham!), x% lighter on startup.

Consider viscosity measured at 40c could be 35 and at 100c its 8.6 for these manufacturer oils compared to say 45 / 8.6 for Mobil, then you can see that during 5 minutes of driving after startup, your oil is always significantly lighter and causing less friction. The difference vs a 30 weight that could have a 40c viscosity above 70 is even more significant. This is way beyond a 0.6% fuel economy difference at operating temp between an oil with HTHS if 2.6 vs 3.0 or V100 of 8.6 vs 10.

So yes, your fuel economy issue is understandable especially in Germany where you've likely received a heavy 30 weight oil.

For your driving, any Japanese manufacturer 0w20 is perfect since you need as thin as possible as you are never at operating temp.

 

[SatinSilver]

So you live in Germany and drive a Prius? How fast have you had it up to on the autobahn? I have a Toyota also. Plus I'm half German.

 

[toneydoc]

Hello Japoc and welcome

I would think that if 0w20 is recommended, then that is what you should use. Why they use 5w30 is it is probably less expensive that the TGMO 5w20.

I would probably run the 5w30 for a year even though it might cost you more petrol usage for the year and have them put the 0w20 in for free next year. I know oil in Europe is expensive and I personally hate to waste oil too early in its cycle. Especially if I am paying for it.

Another oil that if loved by members of this forum is Castrol 0w30 that is made in Germany and seems to hold up real well in usage in the USA.

But again I would use the oil in the car and go with the free oil next year. Let us know what you decide to do. Welcome to the forum of many opinions.

 

[TrevorS]

Japoc, take up the offer of free oil next time but bring it forward by a year!

 

[KCJeep]

Can't help you with your Prius but:

 

[CourierDriver]

Originally Posted By: satinsilver
So you live in Germany and drive a Prius? How fast have you had it up to on the autobahn? I have a Toyota also. Plus I'm half German.
lmaorof. that was good.

 

[Japoc]

Wow... didnt await so many answers and the forum software doesnt automatically send notification emails... (marketing loss for the forum owner...)

Thanks for the welcome!

Donald... PYB? If you mean the proper oil, that would be 0W20 and i thought i would get it a month ago at the checkup... though they put 5W30 in it. Most probably because its cheaper for them and they dont "believe" in differences... really a pity that believe is a reason there. I dont see why Toyota isnt enforcing the correct oil. I mean their cars run worse than they could this way and that should hurt their brand. Im a bit angry about this behaviour. I mean many people want to save gasoline and money and then some cheapsters make them pay more. Not to speak about the environmental thought.

BertieBlue... they added 5W30, not 0W30... but you think 0W30 to 0W20 could make such a difference too? I thought that wouldnt account so much. Though i first need to know what 0W20 to use... when mobil 1 really is so much worse than TGMO 0W20 then i would consider ordering TGMO 0W20/buying it at the workshop directly.

InhalingBullets... i didnt notice problems with the battery yet. Only one time i had to call the help to get started because the battery was fully empty for a reason i couldnt find. That didnt happen anymore since then and it was some time before the inspection was done. So i doubt that its the reason for the mileage increase.

TrevorS... thanks for explaining... what are japanese oils? And is there a table to find the optimum between viscosity and price easily? Maybe it would be interesting to know how hot a prius hybrid gasoline motor (or its oil) could become. When driving full speed its probably the same like any other car so it needs to be prepared for that. So the most important part to look at would be a best viscosity and cold conditions. I found this table: http://www.toyotanation.com/forum/310-7t...tml#post3877881 It says TGMO has a superior VI. Is this value the one i should look at? I mean normally there is no V-Value for 0°C or so which might be a good hint for the viscosity for the cold motors oil.

satinsilver... i only have the Prius since 3 months or so. So i only could try it a bit. I got 192km/h but i didnt want to drive longer to max it out because it was rainy and windy and i didnt feel too secure with that... though the freeway was free at least. I had 3 tracks for me.
I will test it once again im driving alone on the freeway and the conditions are good.
Though i dont see it as a reasonable speed for traveling since the noise of wind and motor isnt much fun then anymore.

tonydoc... im not so sure if i should let the old oil in. I mean 1 liter gasoline costs me 1.50€ and i would pay that on top each 100km...
Im not sure yet if i can get TGMO 0W20 for cheap somewhere. I have read here that in the us you get it for 5$ per Liter only. Maybe i find a cheap source too. I dont know if there is a better oil than that anywhere. I mean an oil that works best with a cold motor. 0W10/5 sound like they look better then they are or are outdated for some reason. At least i read that from the forum.

 

[KrisZ]

Let's do some math first.
Your OCI is 15000km and at 5km trips I'm guessing that you are not hitting the 15000km mark, but I will assume that you are doing 15000km oil changes.
At 1.50 /L of gasoline you will pay an extra of 225 over the 15000 kilometers. The oil alone will probably cost you around 80 euro.

So if you change the oil yourself you will be saving a whopping 145 euros over the 15000km or one year. I think you're over reacting especially since we don't know 100% if it's the oil or just the cold weather.

 

[TrevorS]

Japco, my meaning of Japanese oils are the Toyota, Honda and Mazda 0w20 oils. They all have the very high VI ideal for your driving.

My first choice would be the Toyota oil because it is designed for your engine. I would choose Honda or Mazda if the price difference was too much or even just to experiment to see which one I liked or gave me the best fuel economy.

If Mobil or another brand had a 0w20 with a lower VI, but it was cheaper, I would try that a well as real world fuel economy might be as good as the Japanese 0w20 oils.

 

[A_Harman]

TrevorS has explained the issue well. It is the combination of viscosity at 40C and Viscosity Index that will get your 1L/100km of fuel economy back. Since you drive mostly with the oil below operating temperature, it is at higher viscosity and is hurting fuel economy. The Toyota 0w20 oil was designed specifically to improve fuel economy in the Prius application by having low viscosity at startup temperature. If you can't get the Toyota oil, Mobil 1 0w20 has a pretty high Viscosity Index and is almost as thin at startup temperature. Or you could get on web sites for European oil makers and look up Technical Data Sheets to compare 40C viscosities and Viscosity Indexes and find the best combination of low viscosity at low temperature, low price, and easy availability for you.

 

[BertieBlue]

Originally Posted By: A_Harman
TrevorS has explained the issue well. It is the combination of viscosity at 40C and Viscosity Index that will get your 1L/100km of fuel economy back. Since you drive mostly with the oil below operating temperature, it is at higher viscosity and is hurting fuel economy. The Toyota 0w20 oil was designed specifically to improve fuel economy in the Prius application by having low viscosity at startup temperature. If you can't get the Toyota oil, Mobil 1 0w20 has a pretty high Viscosity Index and is almost as thin at startup temperature. Or you could get on web sites for European oil makers and look up Technical Data Sheets to compare 40C viscosities and Viscosity Indexes and find the best combination of low viscosity at low temperature, low price, and easy availability for you.



A much better way of saying what i was trying to get aross. (yes, i meant 5/30 it was a typo)

I think of oil as syrup. When cold, its thick. Heat it up, it goes thin.
for the 5/30 vs 0/20, the 5/30 starts off thicker than 0/20 and stays thicker than 0/20 when hot, hence from start to finish, your engine has to work harder to puch the syrup around. Given that the Prius (in town traffic anyway) can spend much time below max operating, the difference on the engine laod is more pronaounced (i think this is the VI index coming into play here) 5/30 is gloopier at all temps than 0/20.


i think...

 

[Japoc]

KrisZ... the weather was even colder when i had 0W20... I think saving money is a good reason to change the oil. I mean i would buy better tires to safe a small amount of gasoline usage too. Why let the oil thing slide?

Ok... so TGMO is the first choice, then Honda and Mazda. But shouldnt Mobil 1 be worse when its really 35% thicker at 0°C and 25% thicker at room temperature? Too bad it isnt possible to make a direct relation from that to the gasoline usage. I asked the biggest german automobil club and they told me it costs 3000€ to make a testrun for such things. I really hoped there are studies already so that this behaviour of toyota workshops stops.

Ill try to check prices and availability now. Though im a bit disappointed that there isnt anything better than TGMO 0W20.

 

[KrisZ]

Originally Posted By: Japoc
KrisZ... the weather was even colder when i had 0W20... I think saving money is a good reason to change the oil. I mean i would buy better tires to safe a small amount of gasoline usage too. Why let the oil thing slide?


Ever heard of a saying "penny wise, pound foolish"?


Originally Posted By: Japoc
Ok... so TGMO is the first choice, then Honda and Mazda. But shouldnt Mobil 1 be worse when its really 35% thicker at 0°C and 25% thicker at room temperature? Too bad it isnt possible to make a direct relation from that to the gasoline usage. I asked the biggest german automobil club and they told me it costs 3000€ to make a testrun for such things. I really hoped there are studies already so that this behaviour of toyota workshops stops.

Ill try to check prices and availability now. Though im a bit disappointed that there isnt anything better than TGMO 0W20.

The 35% lighter comment really refers to the 35% difference in viscosity index and that figure does not directly transfer to the actual viscosity difference at a set temperature. Also, that 35% lighter claims does not translate to 35% better fuel economy. According to Toyota's studies it's in the range of 1%-2%.
If you're Prius consumes an extra 1L/100km then it's in the range of 25%+ extra fuel economy. That kind of mileage hit cannot be attributed to oil viscosity.

 

[Japoc]

Its 6.8l now in average... before it was 1l less. So its more 15% more. Thats because i drive only short tracks. When i drive a long track this for sure will be less but the whole point of the oil is that it doesnt get the chance to get hot in order to become a lighter viscosity.

Right, its not translating directly to 25% more fuel economy when using TGMO instead Mobil 1 0W20. Though i wonder what the difference would be in that case. You say its 1-2%? Is that for the difference Mobil 1 0W20 to TGMO 0W20?

I didnt find any source that directly sells TGMO or the 0W20 from Mazda/Honda.

Penny wise... pound foolish... i dont see your point. You know that i would already save a lot when changing the oil now most probably and running 0W20 instead 5W30 for a year. The last M&S Tires i bought were fuel economy C tires. Buying nonames isnt wise when they break fast. So whit a brand that is quality and cheap and have a good fuel economy, why not? Lets say a set of summer tires is good for 40k km. Buying a fuel economy tire with B instead F means they use 0.4l gasoline less per 100km. So for 40k km and 1.5€ per l gasoline that would make 240€ one could safe in gasoline costs. Not much but still something. Thats 60€ more per tire and tires with a good fuel economy arent so much more expensive.

I dont know what you drive and how but why should i pay more than needed? I mean i bought a prius because i like the concept of reusing otherwise wasted energy. I probably wouldnt care much when i would have bought a sports car too.