Took my 2017 Highlander to dealer for oil change and tire rotation at 37K miles. They said that the transfer case and differential required immediate service (fluid change) based on my mileage. I told them that the manual states this was only needed if used under extreme conditions such as used for towing, carrying heavy loads, and use of a roof top carrier. I told them that none of these conditions applied to the vehicle. I was told by the dealer service rep that Toyota recommends that this should be changed at 30K miles. They will let this slide if the extreme conditions were not met but definitely is mandatory to be done at 50K miles no matter what. I again said that the manual doesn't call for this. They said that "Toyota Service" (I believe they were referring to Toyota itself, not the manual) says that this should be done. I would think that the Toyota manual is the "Toyota Service". Who is right? They wanted $158.49 for this service.