finally found the 5w-20 TSB...

[1stToyota]

R2D2,
Because I think we're just more worried about fuel economy and less worried about longevity. Most of the European oil recommendations that I come across are more heavily swayed by ambient temperatures.

I was hoping you had it in mind to do a UOA on your 5w20, first, before you switched to 0w20 to see how they compared. I'm not yet convinced that thin is in when thicker is still being listed as the oil to use in service manuals, owner's manuals and the oil cap, and the thinner oil listed on a 3 year old TSB is still left more as the afterthought.

Just for grins I'll probably not do my 2nd UOA on the Pennzoil YB 5w30, I'll probably test PP 5w20 against PP 5w30, w/o use of the filtermag, of course...still won't trust 0w20 as it's still not listed as suitable oil to use for our Yaris in any service manual, owner's manual or TSB, yet.

EDIT: Or better yet, I'd test my PP 5w30 against a 0w30, if you or somebody else could recommend a really good synthetic 0w30 to use...

Looks like it'll be Mobil 1 0w30 vs. Pennzoil Platinum 5w30
With winter coming soon looks like my first UOA will be the 0w30 :)