That is what I was asking you... if you can or not. The filter housing is so low on the motor that I would think the oil drain out. Perhaps not, I don't know. Now on my Kia Sedona, the housing sits on top of the motor (I wish Toyota had done this) that it would make changing just the element easy!
Actually, All I'm doing is reporting the readings I got back from the oil analysis. Smart individuals can use this raw info as they see fit. The official answer is that the first oil change needed is at 10k miles. That's why I made the comment about this not being proof of early oil changes. Where I'm different is that I am planning on using the oil for extended intervals, so I prefer the first change at 5000, since the next oil change may be much farther on out (depending on sample results at intermediate intervals). On the 2007 Prius, the silicon level drop by about a factor of two for every oil change afterwards till about 25ppm is reached, so I wanted to get an early start on getting to my long term baseline. I'll also add the comment that the 2007 Prius has got to be the most difficult vehicle I have ever had to change the oil for. With it being so involved, not changing the really simple oil filter seems to be a strange choice.
You are correct that on most engines the oil filter sits higher than on the Prius. I put my front tires on ramps so the oil should run to the back of the oil pan. The next time that I change the oil on the Prius I will try removing the filter first and see how much oil drains from the filter housing and let you know.
I must have the best dealer. I took my 2010 in for the brake software adjustment at about 3500 miles. I asked the service writer to do an OC. He said, "Why? This car is good for 10,000 miles". I had to ask him 3 times to get him to agree to do it. He not only assured me that they would use synthetic 0w20, but it also appeared on the bill...a grand total of about 45 bucks if I remember right.
Specifically responding to your question - On all vehicle engines that I've worked on (automobile and aircraft), the oil filter has been located above the oil pan, not in the oil pan. Therefore the only oil you lose in just changing the filter is the oil in the oil filter itself. To drain the oil out of an engine, a oil plug (large screw) is located at the lowest point of the engine pan. Removing this screw allows all the oil to drain out of the oil pan (it does not remove any oil that might be in the oil filter). In may vehicles, the oil filter is screwed in from the bottom, therefore oil cannot drain out of the filter without removing the filter itself. Honestly, I have not changed the oil filter on a Prius. The configuration may be different. Keith
I am not used to these 10K oil changes either. I have continued to change mine at 5k intervals, so maybe it will only be a few more months before I change it again and not a year
The oil filter on the 2010 Prius is different than most cars that I have worked on. The Prius oil filter is just to the right of the oil pan and just about the same level as the bottom of the oil pan. So, the question that is being raised is if you do remove the oil filter without first draining the oil pan, how much oil will drain from the oil pan through the filter housing assembly?