0W-20 OIL......WHY WE USE THIS GRADE OF OIL??

from my first oil change on with a milage of 1566 miles/

 

Umm .... They're "true" if they're within the allowed range of viscosity for their claimed grade, whether they're near the maximum, near the minimum, or right in the middle. That said, you're correct that the European flavors tend not to flirt with the minimums, as "fuel economy" oils often do.

 

I'm still waiting for the post that says "so you think you know more than the engineers who designed the car?".

 

it all funnels down to the criteria the engineers went by/
if it was to meet mpg/co2 emission requirements in the usa & an acceptable engine mileage (like 180.000 miles), they were dead on to recommend 0w-20/

 

That's just it David, the engineers don't have a free rein, I suspect they're pushed by various influences and restraints. How else to explain the variety of oil change intervals, and grades, around the world. Also: dead silence on the subject of transaxle fluid change?

 

I know nothing.

And the engineers are just puppets...?

Let's just use whatever oil we feel like using. We will STILL get somewhere between 45 and 70 MPG!

 

This oil situation is pretty confusing. Seems like a lot of politics involved in the design of the car. I would like to use what the owner's manual recommends, but now I'm not so sure.

And now I see that thread about oil leaks in a 2013 Prius. Bad seals/gaskets? Could using a thicker oil minimize those leaks, or prevented the leaks?

 

In addition to politics there is also profits that have a great factor ( sometimes overriding). As someone who worked for a supplier of Toyota, when we had something new or innovative to offer, do you think they gave immediate approval?

They used the 3 factors that we are all familiar with when making a financial decision:

1) is it less expensive than what I currently buy
2) is it something that is a better value at the same price
3) is it something I am willing to pay more for that offers me some advantage

You can imagine which of the 3 above was least chosen

 

My opinion: go by the recommendations in the owner's manual and stop worrying. There are millions of 2ZR-FXE-engined Priuses on the roads; the few people who post here with oil consumption problems or gasket leaks are not a representative sample. Even "trustworthy" sources such as Consumer Reports, who conduct random sampling, do so from the pool of people who already subscribe to CR--which means their data can't be reliably extrapolated to American owners as a whole (CR subscribers may be more likely to notice minor problems like oil consumption, for instance, or more likely to buy certain models of vehicle recommended by CR, or any number of other variables which cannot be controlled). It's even worse on a website like this, where people could sign up because their car is burning oil or has an oil leak, thus making this seem like a bigger problem (i.e. likelier to happen to you) than it actually is.

 

The words if the service manager are still ringing in my ears...

"All Toyota engines leak oil! I wouldn't have a job if they didn't!"

I wonder if that guy got fired?

 

My only concern is that not being a Full Synthetic Oil.

 

Is it ok to use something that is not Full Synthetic?

 

Yes. Toyota gives specs for the oil, but never insists on synth.

that said, in 0w20 I think they all are synth?

 

"Maybe" it's the country, but my owners manual say synthetic.... But what does Toyota know?

 

I am not really sure if all 0W-20 are fully synthetic.

For example, Liqui Moly 0W-20 Special Tec AA 0W-20 just says it is "Special Tec" and "High Tech Synthese Technology", both I guess are their proprietary or marketing terms.

On the other hand, Mobil 1 mentions their 0W-20 is Fully Synthetic on the label.


I have found similarities in some other brands too. If it is fully synthetic, shouldn't the manufacturer mention it since it is more expensive to produce?