No, this is not an oil debate.

I think it's to do with the ambient temperatures and the quality of oil available.

 

The usual suspects, ie: mpg targets, differences in owners willingness to keep up with maintenance (real or not), and yeah different climates, except implementation of the latter doesn't seem to be much connected to reality.

 

In my Prius Owner's Manual the explanation for 0W-20 weight oil is for best cold weather starting and best fuel economy. No mention is made of wear reduction being a benefit of 0W-20 oil. The manual also includes a chart with the outdoor temperature range of 0W-20 oil. Therefore, we are using 5W-30 weight for better wear reduction and will confirm results by oil analysis.

 

I'm sure the lawyers had their hand in this as well...

 

Australia has a chart showing which grade is applicable to what ambient temperature. It lists (SAE) 0W-20, 5W-20, 5W-30, 10W-30 and 15W-40.

There are 2 pages of explanations including "...lower value before the W allow for easier starting of the engine in cold weather." AND "... higher viscosity ... high speeds, or under extreme load conditions".

 

I've thought about this for a while. It's a little disturbing: a very conventional statement in Oz, vs the terse 0W20 and nothing but statement in North America.

 

Yes, it would be less confusing if the recommended viscosity was the same across the world.

I'll stick with the 0W-20 as per the owners's manual... and it better have the wear protection I expect. But to be honest, I kinda like the sound of "5W-30" better. That's what my V6 Camry used. It gets pretty darn hot here.

"The Corporate Average Fuel Economy (CAFE) standards are regulations in the United States, first enacted by the U.S. Congress in 1975, in the wake of the Arab Oil Embargo, to improve the average fuel economy of cars and light trucks (trucks, vans and sport utility vehicles) produced for sale in the United States."

I'm sure this has been asked a dozen times... What is the recommended oil viscosity for the previous generations of Prius? Is it the same as the Gen4?

Some people may wonder (myself included) will 0W-20 provide superior (or adequate) wear protection for the long-term life of the car? (10-20 years?) I guess we have to trust the Toyota engineers. And the owner's manual says 0W-20 is good to go in ALL temperature extremes.
And in some owner's manuals, the tire rotation instructions are different from what we have in our North America version of the Prius. (I saw that in another thread.)

I'm looking at my owner's manual again, for the 10th time... Page 730.

It shows a firm recommendation for 0W-20 oil. However, "An oil with a higher viscosity may be better suited if the vehicle is operated at high speeds, or under extreme load conditions." ( No mention of frequent stop & go, city driving, such as a Taxi would have.)




​

 

They do allow 5W-20 in emergencies, if you really can't find 0W-20.

Their "nothing but statement" may be due not only to CAFE, but also to feeling North Americans aren't bright enough to properly apply conventional latitude- or temperature-related recommendations.