[newhavenpatriot]

Thanks for the replies, everyone! I also just found a Toyota Service Bulletin stating that all 2006 and 2007 model year vehicles with certain engine types (NZ series is included, which is what my 2007 Yaris has, the 1NZ-FE engine) should be using 5W-20 oil instead of 5W-30. They say it offers better fuel economy, engine protection, and increased cold starting performance. My oil cap and owner's manual say 5W-30, but that could be because they were printed before the bulletin came out. The bulletin has a date of March 29, 2006, and my car is a 2007, but I know that the model year always comes out the year before, so my 2007 Yaris was available in 2006. This means it was probably constructed in 2005 and the owner's manual was printed in 2005 or early 2006, in which case this bulletin hadn't been released yet.

I think I'm gonna bring a printout of the Toyota service bulletin to Valvoline next time I'm due to have my oil changed there. I'll ask them to use 5W-20 instead of the 5W-30 they had been using.

If you want to check out the bulletin, it's Toyota Service Bulletin EG018-06.