My Sienna started showing low oil pressure right after the factory warranty expired. The Toyota dealer checked my car, they cannot figure out the problems except for a very low oil level. I have to change oil every 3 month, and recently every month. The dealer checked again, and suggested replacing with a new engine with the cost around $6700. I heard Toyota 's engine has the problem of excessive oil consumption. But they denied on my car. Anyone has the suggestions, please inform me! Thanks very much!