More On OW20 Oil Confusion

I'm confused after skimming this. If you live in a hot weather place is the recommendation a heavier synthetic like 5w30? Or because of the nature of the engine stick with 0w20.

Our record low (all temps in F) is -2, we only have 25 days a year bellow freezing and I don't think I've driven here colder than 20 (I fly to snow and am in a rental car then). There are over 100 days a year over 90, last year 67 over 100.

 

I guess I have two reasons for thinking a heaver oil might be better under some conditions:

1. Read the last sentence or page 560 in the Owner's Manual. They don't say what conditions or speeds they are referring to but I keep thinking that 75 or 80 MPH on an Arizona freeway when it's 110 degrees F might qualify.

2. It's pretty obvious that Toyota, and other companies, have gone to thinner oils, 0W20 or 5W20, to get higher numbers on the fuel efficiency and emission control tests. When they do that the EPA requires that they pass the oil viscosity recommendation or requirement on to the customers who buy and use the vehicles and list no other choices. There is an EPA letter that actually states this which I ran across on one of the Toyota truck forms, don't remember which one right now. That being true I wonder if 0W20 really the best oil for long trouble free engine life, especially in hot summer weather?

I don't know the answer. I am tempted just to use 0W20 all year around and forget about it. But in my case it would be pretty easy to put in heaver oil for summer so I brought up the question.

 

FWIW here in France we have the same 0W20 oil recommendation yet the oil change interval in 15000 km.
I'm having a hard time imagining why the same car using the same oil would require twice as much oil change in the US than in Europe.

 

I also got the Mobil 1 deal at Advanced Auto. I picked up enough for three changes. I think I may use the OEM filters.