synthetic oil mixed with regular oil

1. Nope. Just drain and fill. Make sure they stamp your service record book.

2. Don't put in 3.9 quarts. Put in three quarts. This fills the system halfway between the "ADD" and "FULL" marks, which is both perfect and perfectly convenient. Funny, in'nt? Almost as if Toyota designed it that way... :_>. I had the dealer do this even though they can meter it out; filling it right to the top is just a game and not worth the risk of overfilling.

Annoyingly, the receipt they gave me reads "4 QT MOBIL 1 10W-30", which is of course both the wrong amount and the wrong viscosity. The service manager explained that this is boilerplate wording from a template supplied by Toyota, which sounds kinda like bulldada. I haven't called the Toyota Customer Experience line to inquire. But they did put in the correct amount (I checked), and he insisted that they really did use 5W-30 and that "new receipt templates" were coming from Toyota in November. We'll see whether the next one reads correctly. And hey, if the engine explodes because of incorrect oil, it's their nickel.

 

I ask the person changing the oil to add 3.5 quarts; I take home the remaining 0.5 qt and top it off to 3.9 quarts. Note that 3.0 is almost 3/4 of 3.9, which means that you have 25 % less oil working in the engine.

The topic of regular vs. synthetic oil has been discussed at length here and no one has been able to demonstrate an advantage of the latter over the former for the Prius ICE. Seems to me that using synthetic oil and/or premium gas are ways of throwing away what one has saved on gas.

 

<div class='quotetop'>QUOTE(jamarimutt\";p=\"43555)</div>

I never used synthetic oil before 30k or less. But I used sythetic brend oil from Mobile one before and work great.