So I hit 30K on my lovely Prius and since the Toyota care free oil changes are up it was time to do it myself. I purchased an Assenmacher Toy640 filter wrench that I learned about on this forum and bought a new washer for the oil pan and a filter and O-ring from a local dealership. My first red flag came up when I took off the oil pan nut and found that it did not have a washer at all. I drained the oil and then began to tackle the filter housing with my $17 filter wrench. I spent way too much time trying to get that thing to budge, but had no luck. I waited until my neighbor came home and he gave it a try (we are both in the 190-200 lb range) and he was at a loss. He went home and grabbed a bar that we tried to use as leverage and still couldn't get it to budge. So I put my oil back in (I had just purchased a new oil resevoir so it was uncorrupted) and I plan on going over to the dealership tomorrow AM that did my last change under Toyota Care to ask them to explain to me how this happened. My guess is one of three things: Either they didn't put the O-ring on, didn't lubricate the O-ring, or used some kind of power tool to torque that thing back on. Considering torque spec on the filter housing is 18 lb/ft, this is ridiculous. While I am not a mechanic, I have done my own oil changes before and just did one last week on my XJ Cherokee. I am at a loss.