By Lowering your oil level by 8 oz. Is it worth it and what did you notice by doing this? Pro's & CON's .
When I change the oil - using the dealership filter - putting in 3 litres will put the level about halfway between the Add and Full dots. If I use 3.3 litres, that puts the oil level on the Full dot No difference in fuel economy that I can determine I'm now fairly convinced the "overfill" problems reported for the Prius, really have to do with how quickly the oil is put in. Eg say a dealership or Iffy Boob place with an automated bulk dispensing oil system Flood the cylinder head with motor oil, the excess can end up in the PVC vent or suction line, and be gulped into the intake. Take your time adding oil, I allow 10 mins to slowly add 3 litres
I honestly don't see how there would be a measurable difference in FE based upon where the oil level is between the two marks on the dipstick. Anywhere between the two marks is acceptable as shown in the owners manual. What you should avoid is overfilling the level; the level should not be above the top mark.
It was slightly over the fill mark, by about a fingernail. Has been in for about 8k, no problems, still getting 52+ mpg.
Near as I can tell, it is an issue of overfill. My experience is that 1/4 inch, about 5 mm is enough to have an impact. Right on the "F" seems OK and less than "F" and above "E" is perfectly OK. Under "E" has no effect other than to risk potential engine damage and wear out the remaining oil sooner. Bob Wilson
I used to put in 4 litres and now put in 3.5 litres. With 4 the oil ended up above the full line by about 3/16". I saw -NO- difference in mileage. I now put in 3.5 litres just to be able to say I'm "doing it right". I use the Toyota brand oil filter. I also put in one litre of 10W30 Mobil 1 and 2.5 litres of 5W30 Mobil 1. I'm still using up the anti-Prius' oil left over. This also made no difference in mileage. Some members of this forum need to "chill out".
