Use of 0w20 Motor Oil In Very Warm Climates

Awesome!

 

It honk you offer good insight. I would not block anyone or discredit what they say, as all of this is opinion, but offers the reader more to think about. I appreciate your insights.

 

I don't agree. The engineers have approved other grades for use with this engine in other countries. But to comply with very strict US emissions laws, Toyota doesn't list the other grades. The low end of the viscosity index describes the oil's viscosity at 32F. This is important for reducing emissions and engine wear during cold starts. In much of the US, a Prius cold starts below 32F, even at 0F and below!

This is important because it's necessary for the oil to be thin enough to flow freely through all the oil galleys to the valves and bearings during startup. But in Arizona, ambient temps are way higher, and it's uncommon to start the car below 60F.

But when oil gets hot, you run into a completely different problem: The oil now thins so much that it won't adhere to metal, so it no longer provides a film over the valve guides and bearing races. Your thinking is that the engine never exceeds 212F or even 190F. And I know you've been on PC for a long time and you have my respect. However, I think that coolant temperature doesn't tell the whole story, because it's the temp at only one location. The engine gets hotter than 190F as evidenced by the fact that the coolant temp is quickly raised from an ambient temp of <100F to about 190F, despite being circulated to cool through airflow. Second, if the car moves slowly or stops when it's hot, the radiator has very limited effect on reducing engine temperature, and so the extreme parts of the engine, like the crank bearings and valves, will be far, far hotter than 190F.


All this is to say that I believe the engine's designer would probably advise an AZ resident to use a higher viscosity oil, especially in summer.

HOWEVER, the Prius requires a special type of oil: ILSAC GF-5. Irrespective of the viscosity, this designation is the most important thing to look for. But according to Mobil, although they have many formulations of Mobil 1 which meet these requirements, only two, the 0W20 and 0W30, have the low zinc content for "Advanced Fuel Economy." So if I lived in AZ, I'd try the Mobil 1 0W30 Advanced Fuel Economy oil.

Mobil 1 Comparison Table

 

^ This. It seems to me there's more than just engineering at play in the North American oil spec.

 

Even in Phoenix, running 0W-20 won't damage your engine. The 5W-30 won't damage your engine, either, but it will hurt the mileage. The operating temps for the Prius engine don't get that high and it has a well-designed cooling system. Australia gets no hotter than the SW desert areas of the US, but the country deeply favors thick oil.

 

hello from Slovakia... why are you afraid about other viscosity than 0W20? There are other parameters more important than " 0W20".... in hot climate and for highspeed driving we use oils with higher viscosity and especially with higher HTHS viscosity - ACEA A3... for example I use 10W30,10W40 or 5W40 API SN- GF5, ACEA A3 - no problem with higher viscosity....
and petrol consumption vs oil visco? Oh... in my country today is price for 1liter of 95 octan petrol 1.2Euro, maximum was 1.4Euro for 1 liter of petrol... driver is most important parameter for consumption not oil... I buy hsd not for low cons but for low cost maintenance...

 

it's a common knowledge that pistons run at 150C or higher.

how about the epidemic oil consumption? don't you consider that subtle damage? as for the operating temps for the Prius engine, see above.

 

Stop worrying and just use the 5W30. I'm contemplating 5W40 for summer that it gets hot because fuel economy honestly will be nothing than a few dollars per 6 months. Driving more economically would have more of an impact to saving fuel.

 

Add, if oil temperature were truly critical, there would likely be an oil cooler too.

One can always add this aftermarket, but this would introduce additional unnecessary complexity. Don't forget, any engine warranty claim will likely be voided by Toyota; unless the engine oil cooler were removed prior to presentation at a dealership.

Didn't you get the memo?

The Fast & Furious 9 will feature eco-drifters! A tricked out Toyota Prius (Nos, turbo, engine oil cooler, engine oil temp gauge in user selectable LED color, etc) to compete against other hybrids and non-hybrids for the International Drifting Title. Can't wait!

 

Yeah....
I saw that memo.

They're going to call it the Electric Slide series....

 

My guess would be the problem isn't high operating temps, but the low tension rings allowing blow-by and degrading the oil, which causes deposits, poor ring seal, and oil burning.

 

my interpretation is different. low tension rings are easier to get stuck in the grooves by coked oil/unburnt fuel. high operating temps (inside the engine, not the coolant part) could be an issue when someone takes this little car and push it to 100mph in hot summer and especially when uphill. thin oil can also play a part as thinner oil = thinner oil film on cylinder liners = less oil circulation in piston grooves. remember that oil thins out even more with higher temps.

 

Yes, it could be, I'm just speculating.

 

I consistently drive this car at 108 to 116 miles per hour. I consistently hold my foot to the floor for 10 minutes stretches without letting up on a daily basis. The temperatures here get up to 98 Degrees and I often times pull a trailer. I put at least one motorcycle on an open trailer and consistently do over 90 miles per hour. I hold this engine is 5200 RPMs for extended stretches sometimes up to 11 hours stopping only to refill the tank. My fuel economy without a trailer is 33 miles per gallon and about 22 with a trailer What oil would you recommend?

 

I would recommend slowing down. Any reason for the big hurry, especially when pulling a trailer?

To answer your question, I use 5w-30 synthetic in Northern California which will work well on FL. With your quoted driving style, I would worry about oil consumption and other wear and tear on the car most of us will not see.

 

if it's still running, one would assume you're using the right oil....

BION
StarCaller

 

well, for how much longer?

 

I did this with my 2nd generation Prius since new and it 210000 miles someone totaled it. I now have a third generation Prius with 170,000 miles that I bought used and I run them both spend at the rev limiter all the time. My 2nd generation Prius motor was still tight and quiet and didn't use any oil. My 3rd Generation Prius is running similarly. It's still purse like anybody else's. Sometimes if you run it for an extended stretch with the trailer and the throttle pinned wide open the computer will trigger the motor to run it only 4500 RPMs. This might be a safety for the temperature of the electrical.

 

I also wonder if burning oil is related to the problem with the EGR/PCV valves.

 

It is a contributing cause if nothing else.