3 quarts is most convenient, and puts it halfway between the ADD and FULL marks. No topping off required.mrv said:I'll note that Priustek on the yahoogroups has stated that the Toyota-recommended 3.9 will put you right at the full mark. The suggestion is to use 3.5, and then top up as needed.hyperion said:What's pretty high? If it's a 16th of an inch it is probably the same as 80% of the Prius's who have had their oil changed by Toyota. They are all adding 4 qts at the change instead of 3.9. I'm surprised they just don't stick in a 4 qt. dip stick.
You can get the 3.9 if you check the car with the service manager after oil change when he informs you that the small amount doesn't matter and a "gosh" more is better than a "gosh" less. Whether you want to take his word for it or not is up to you.