Don't assume your Toyota dealer will use the correct oil.

Hmmm.... Anal Prius drivers. It's bad enough that there's crap-loads of spent motor-oil being pulled from crankcases every 5000m/8000k un-necessarily. As per their dealer recommendations. With full-synth in the CC, I can go a year or 16000km... Would you like me to come to your storm sewer and dump the extra 8.6L of motor oil down there and leave the spent oily media in your driveway? I, too, have read a lot of info about lubrication of engine parts over the years, not just motor oil. Those numbers aren't just 'chaff'; they exist for a reason and there's a reason WHY the engineers say why to use 0W20 full synth rather than 5W20 semi or conventional... It's called VISCOSITY, SHEER, COKING, SLUDGE CONTROL, COLD START [important w/ a hybrid's constant start/stop cycles!] and OVERALL DYNAMIC/STATIC FLUID STRUCTURE UNDER STRESS. Toyota uses a 'trick' to say that their 5W20 is semi-synth.... They add an additive to conventional bulk oil to 'say' it's just like a synthetic oil. Well, my Prius doesn't act like it has the proper oil in the CC, especially during winter months! My gas mileage plummets to around 42-45mpg city and rebounds to around 63 hwy. It behaves like a conventional car!!!! Please note that these are imperial measurements; US figures would be 20% LESS! And I live near Vancouver, BC, where it's not cold; the lowest temp we've had all year is 18F...for 2 days! All I want is my car to perform like Toyota says it should; if it should be getting near 68-72mpg, then bring it on! So, I will be taking my own 0W20 full-synth and my own long-life media filter to my dealer for my next 'free' oil change. Then my 2010 Prius should be getting the same results as the one I drove in LA/San Diego: 53mpg US or 64mpg imperial [4.4l/100km].... And to compare a Prius to a truck, conventional car, or motorbike is to compare a hand calculator to a laptop computer. And mechanics look at Prius' with great disdain anyways; that which they don't wish to understand, they ignore. Now if Toyota resurrected the Celica or Supra, those gearheads would be all over it! But, when I go to my Toyota d/s, I have never dealt with the gearnogs. Just SA's who say 5W20 with a dash of sauce is just the same as 0W20 full-synth.... WRONG! Hey, Duffer! Full discloser. Do you own a Prius or are you just a troll?