One problem related to engine oil leaking has been reported for the 2004 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota Prius based on all problems reported for the 2004 Prius.
Every time I get an oil change I make sure that the right amount of oil gets put in the engine. I usually get an oil change every 3000 miles regardless of what the oil manufacturers recommend which is usually 5-7 thousands miles. For the past year I started noticing (usually by the oil service tech) that more and more I'm running low on oil. It started out with a half to one quart of oil missing between oil changes to now 2-3 quarts missing between oil changes. I understand that my 2004 Prius is approaching 200k miles but I have always taken great care of my car and now all of a sudden I'm having to top off the oil every week. There's absolutely no oil leak and I don't see any white or black smoke from the exhaust. I'm pretty disappointed because I have just recently had to replace my hybrid battery ($2800) and if the engine is going to need to be replaced as well than I mind as well just junk it as it won't be worth it at that point.